ARCHITECTURAL INGENIERIA SIGLO XXI, LLC, A FLORIDA LIMITED LIABILITY COMPANY, SUN LAND & RGITC LLC, A FLORIDA LIMITED LIABILITY COMPANY F.K.A. SUN LAND RGITC, CO., PLAINTIFFS-APPELLEES,

v.

DOMINICAN REPUBLIC, A FOREIGN STATE, INSTITUTO NACIONAL DE RECURSOS HIDRAULICOS, A FOREIGN GOVERNMENT AGENCY, DEFENDANTS-APPELLANTS

DUBINA, Circuit Judge: These appeals arise from an action brought by two Florida companies against a foreign nation and one of its instrumen-talities under the Foreign Sovereign Immunities Act, 28 U.S.C. §§ 1602-1611.

Plaintiffs Sun Land & RGITC LLC and Architectural Ingeniería Siglo XXI, LLC sued Defendants Dominican Republic and INDRHI for breach of contract and unjust enrichment related to an irrigation project in the Dominican Republic.

Because the Dominican Republic and IND-RHI did not timely answer the complaint, the district court entered a default judgment in favor of Sun Land and Architectural, awarding damages that cumulatively exceeded $50 million.

Eight days after the entry of the default judgment, the Dominican Republic and INDRHI entered an appearance; and ten days thereafter, they moved to vacate the default judgment for excusable neglect under Federal Rule of Civil Procedure 60(b)(1).

The district court denied their motion, and they timely appealed.

While that appeal was pending, the Dominican Republic moved to vacate the default judgment for voidness under Rule 60(b)(4).

On reconsideration, the district court denied the motion on the merits, finding that the foreign nation had waived its sovereign immunity.

The Dominican Republic timely appealed that ruling as well.

We consolidated both appeals and now reverse the district court’s orders on the Defendants’ Rule 60(b) motions. I.

Sun Land and Architectural’s breach-of-contract action is based on several documents, which they collectively refer to as “the Contract.”

Because whether the district court had subject-matter jurisdiction over the claims against the Dominican Republic depends on the nature and content of these documents, we begin with an overview of their key terms. A.

In 2000, INDRHI proposed the construction of an irrigation project in the Dominican Province of Azua.

This project, commonly referred to as Azua II, was intended to provide irrigation to an area totaling 3000 hectares.

INDRHI and STP (the Technical Secretary) invited contractors to bid on the project.

Each bid had to be for a turnkey project that, among other things, provided for the financing necessary to complete the project.

To arrange the financing component of its bid, Architectural asked Sun Land to participate.

Ultimately, its $51.8 million bid for the Azua II project was the winning bid. B.

In November 2001, the President of the Dominican Republic issued Special Power 691-01, authorizing the Technical Secretary and INDRHI — “in the name and representation of the Dominican State” — to enter into two agreements regarding the Azua II project: (1) a financing agreement with the Florida Export Finance Corporation and other commercial banks, with the guarantee of ^ the Export-Import Bank of the United States, to obtain the funds needed to complete Azua II; and (2) a commercial agreement with Architectural to provide the service^ needed to complete the Azua II project. ^ C.

In February 2002, INDRHI, the Technical Secretary, and Sun Land entered into a purchase agreement.

Under this agreement, INDRHI agreed to buy the “Products” (e.g., the raw materials) and the “Services” (e.g., civil engineering, architectural designs, and supervision) needed for the Azua II project from Sun Land.

To fund this purchase, the Technical Secretary agreed to obtain financing through Sun Land, an authorized agent of the Export-Import Bank.

In return, INDRHI and the Technical Secretary agreed to pay Sun Land the total purchase price of $51.8 million, an amount that was “guaranteed with the full faith and credit of the Dominican Government.”

Several other provisions of. the purchase agreement are relevant here.

First, the purchase agreement made plain that the Technical Secretary had been “empowered by the Executive to sign [that agreement] with the Full Faith and Credit of the Government on behalf of the country.”

Secpnd, Sun Land had “an absolute right to subcontract” any of its obligations or duties under the purchase agreement; and INDRHI and the Technical Secretary “agree[d] to execute any additional documentation [Sun Land] ... may deem necessary to effectuate the terms and conditions of this agreement.”

Third, INDRHI and the Technical Secretary “acknowledged and agree[d]” that they were not entitled to “immunity on the grounds of sovereignty or otherwise” because the activities contemplated by the purchase agreement were “commercial in nature rather than governmental or public.” INDRHI and the Technical Secretary — “in respect to themselves” — then “expressly and irrevocably waived any such right of immunity.”

Fourth, the parties submitted to the jurisdiction of the federal court sitting in Miami, Florida for any action “arising out of or relating to this agreement or notes or any of the transactions contemplated thereby.”

Fifth, the parties agreed that Florida law would govern the construction and enforcement of the purchase agreement.

Sixth, INDRHI and the Technical Secretary “designated, appointed] and empowered]” the Dominican Ambassador or any Dominican Consul to receive service of process on their behalf.

They also agreed that service of process could be made personally or by mailing or delivering a copy of the summons and complaint to the Dominican Ambassador, any Dominican Consul, or the address listed in the purchase agreement.

Once executed, the purchase agreement was submitted for legislative approval.

In November 2002, the Dominican National Congress passed a resolution approving the purchase agreement, which the legislature described as a document executed by “the Dominican State, represented by the Technical Secretary of the Presidency ... and [INDRHI]” under Special Power 691-01. D.

In March 2002, INDRHI and Architectural entered into Contract 10375 for the studies, design, and construction of the Azua II project.

According to the preamble — “an integral part of’ Contract 10375 — the Technical Secretary had instructed INDRHI “to serve as the executing entity” for the Azua II project.

Also, as both its preamble and articles made clear, Contract 10375 had been entered into and was to be performed in accordance with the purchase agreement.

Under Contract 10375, INDRHI did not submit to U.S. jurisdiction, agree to a special arrangement for service of process, or explicitly waive its sovereign immunity.

Instead, the parties submitted to jurisdiction in the courts of Santo Domingo, agreed that Dominican law governed the agreement, and provided that certain disputes should be arbitrated in the Dominican Republic.

Contract 10375 was ultimately replaced with a more comprehensive document and thus is not part of what Sun Land and Architectural call “the Contract.”

As a result, Sun Land and Architectural do not allege that the Dominican Republic or INDRHI breached Contract 10375.

Even so, this document remains relevant here because several documents that are part of the Contract explicitly incorporate Contract 10375’s terms. E.

In February 2004, INDRHI, Sun Land, and Architectural executed the protocol for the execution of the purchase agreement.

The protocol explicitly superseded Contract 10375 and set forth each party’s responsibilities regarding the Azua II project, including the construction and payment procedures.

After acknowledging that “there [we]re several Agreements that relate[d] to and [we]re material to the construction and financing” of the Azua II project, the parties expressly provided that the terms of the purchase agreement trumped any conflicting terms in the protocol.

The protocol, like the purchase agreement, included several additional provisions that are relevant here.

First, INDRHI “acknowledge^] and agree[d]” that it was not entitled to “immunity on the grounds of sovereignty or otherwise ... in any legal proceeding arising out of or relating to THE PROTOCOL” because the activities contemplated by the protocol were “commercial in nature rather than governmental or public.” INDRHI then “expressly and irrevocably waive[d] any such right of immunity.”

Second, the parties submitted to the jurisdiction of the federal court sitting in Miami, Florida for any action “arising out of or relating to this PROTOCOL or any of the transactions contemplated thereby.”

Third, the parties agreed that Florida law would govern the construction and enforcement of the protocol.

Fourth, INDRHI “designated, appointed] and empower[ed]” the Dominican Ambassador or any Dominican Consul to receive service of process on its behalf.

It also agreed that service of process could be made personally, or by mailing or delivering a copy of the summons and complaint to INDRHI “in care of its agent designated above.”

With the purchase agreement and the protocol in place, work on the Azua II project was ready to begin. F.

In March 2004, Architectural received word from INDRHI to begin the Azua II project, and it did so.

Over the next 30 months, Architectural worked on the irrigation project as INDRHI directed, which included complying with its numerous orders to cease all work as well as its countermands to recommence.

In March 2006, INDRHI sent a letter to Architectural approving an itemized list of the “Components of Works in New Contract” that updated and expanded the scope of the Azua II project.

Sun Land and Architectural have characterized this letter at least three different ways: (1) in their complaint, they called it “an Agreement”; (2) in their motion for default judgment, they referred to it as “a [N]ew Contract”; and (3) in their brief on appeal, they define it as “the ‘Amendment.’ ” Here, we refer to this document as “the Amendment.”

With the addition of the components referenced in “the Amendment,” the total cost of the Azua II project ballooned to $106.1 million.

Once financing for this expansion was secured in June 2007, IND-RHI instructed Architectural to begin working on the project again. G.

In November 2007, INDRHI and Architectural entered into the first of three addenda.

The first addendum covered structural repairs to sections of the Yaque del Sur-Azua Canal, a system of water pathways in the geographic region of the Azua II project.

The total cost of this work was $63.4 million Dominican pesos.

After Architectural performed part of the work contemplated by this addendum, it presented INDRHI with an invoice for $40.1 million Dominican pesos, which was paid in full.

In January 2008, INDRHI and Architectural entered into the second addendum to repair sections of the Yaque del Sur-Azua Canal damaged by Tropical Storm Noel.

Architectural performed the work contemplated by this addendum and presented INDRHI with an invoice for $44.5 million Dominican pesos, which was paid in full.

Finally, in July 2008, INDRHI and Architectural entered into the third addendum to repair sections of the Yaque del Sur-Azua Canal damaged by Tropical Storm Olga.

After Architectural performed the work contemplated by the addendum, it submitted a partial invoice to INDRHI for $55.1 million Dominican pesos, which was paid in part.

INDRHI still owes $18.4 million Dominican pesos on this invoice.

Each addendum purported to modify the terms of Contract 10375 between INDRHI and Architectural.

For example, the third addendum provided, “All other remaining Articles of Contract 10375 that have not been modified remain in full effect, the same as the Documents of the Contract that are not modified by effect of the present Addendum.”

That addendum also provided that it would “hot have to be ratified by any other party, due to the fact that the necessary funds involved in [the addendum] will come directly from the Dominican state.”

None of the addenda expressly refer to either the purchase agreement or the protocol.

According to Sun Land and Architectural’s complaint, the purchase agreement, the protocol, and the three addenda comprise “the Contract.”

On appeal, as in the district court, they also contend that “the Amendment” is part of the Contract. H.

In October 2008, INDRHI sent a letter to the legal counsel for the Dominican Executive Branch.

In this letter, the agency described Architectural’s performance as “satisfactory, fully complying with their obligations as principal contractor, despite the lack of payment of several invoices.”

The agency also noted that Sun Land’s work had been “executed without any problems.”

Even so, in February and June 2009 as well as in October 2010, INDRHI sent Sun Land and Architectural correspondence attempting to terminate their work under the protocol and the first and third addenda.

In 2011, a Brazilian company was hired to complete the Azua II project.

II.

In February 2013, Sun Land and Architectural filed this action against the Dominican Republic and INDRHI.

The next day, service of the original summonses and complaint was made on the Office of the Consulate General of the Dominican Republic in Miami, Florida.

These documents were received by an “auxiliary consul,” a person performing clerical duties at the consulate, who then delivered them to Gina Lacayo, “the assistant” to the Miami Consul General.

This assistant position is a secretarial position, and there is no evidence that Lacayo had any management duties at the Miami consulate.

Indeed, at the time of service, Lacayo had served in this secretarial capacity for only three months, though she had been an auxiliary consul (a clerical position) for nearly 12 years before taking this job.

After receiving these documents, Lacayo contacted Ramon Burgos, a Dominican lawyer in Santo Domingo, who worked as an assistant legal counsel to the Dominican government.

According to her declaration, she did so to confirm her understanding that the Miami consulate was not authorized to accept service of process.

Without reading the complaint herself or providing Burgos a copy to review (and apparently he never asked to see the complaint), Lacayo explained to Burgos that the Miami • consulate had mistakenly received legal documents naming the Dominican Republic as a defendant in a U.S. legal action.

Burgos then confirmed her understanding that under both Dominican law and the Vienna Convention, the Miami consulate should not have received or accepted service for a lawsuit against the Dominican Republic.

Having confirmed her understanding, Lacayo called Sun Land and Architectural’s counsel to explain that the Miami consulate was not authorized to accept service of process.

During this call, Plaintiffs’ counsel explained that the Miami consulate could accept service in this case because it was contractually authorized to do so.

But Lacayo disagreed.

Given her conversation with Burgos and the Miami consulate’s longstanding policy against accepting service of process, she suggested that Plaintiffs’ counsel send these documents to the Dominican Embassy in Washington, D.C.

In early April, Sun Land and Architectural mailed the Dominican Ambassador in Washington a certified letter that included copies of the summonses and complaint and emailed him a copy of that letter without attaching a copy of the complaint; a copy of this letter was also sent to the Miami consulate.

When Lacayo received this letter, she again called Plaintiffs’ counsel to notify him that the Miami consulate was not authorized to receive service of process for the Dominican Republic and to request that he stop sending legal documents to the Miami consulate.

According to counsel’s affidavit, Lacayo “advised that there would be no response because the Defendants had not been properly served, and told me to read the Vienna Convention.”

Lacayo, in contrast, explained in her declaration that she “never said that the government of the Dominican Republic would not be taking any action in response to the Complaint and Summons. I was not then, and I am not now[,] authorized to speak on behalf of the government of the Dominican Republic.”

In any event, La-cayo said that in light of the April letter, it was her understanding that the Embassy was handling this matter. In mid-April, the clerk of the district court entered default and mailed a copy to the Miami consulate.

Sun Land and Architectural moved for a default judgment a month later. A process server delivered copies of this motion to the Miami consulate.

Although Lacayo received them, because she believed that the Embassy was handling this matter, she simply filed the motion.

Sun Land and Architectural also assert that they sent copies of this motion to INDRHI and the Dominican Republic Ministry of Economy, Planning, and Development (formerly known as the Technical Secretary) by Federal Express.

In June, four months after Lacayo, the Miami Consul General’s secretary, first received service of process, the district court entered a default judgment against the Dominican Republic and INDRHI, and they were served with a copy of this judgment at the Miami consulate and by Federal Express in the Dominican Republic.

Eight days later, they entered an appearance; and ten days thereafter, they moved to vacate the default judgment for excusable neglect under Rule 60(b)(1).

The district court denied their motion, finding that they had not established a good reason for failing to respond to the complaint.

The Dominican Republic and INDRHI timely appealed.

While that appeal was pending, the Dominican Republic moved to vacate the default judgment for voidness under Rule 60(b)(4).

On reconsideration, the district court denied the motion on the merits, finding that the foreign nation had waived its sovereign immunity.

The Dominican Republic timely appealed that ruling as well.

We consolidated both appeals.

III.

Several standards of review govern these appeals.

We review jurisdictional questions de novo, Beg v. Islamic Republic of Pakistan, 353 F. 3d 1323, 1324 (11th Cir.2003), and the district court’s factual findings for clear error, Aguamar, S.A. v. Del Monte Fresh Produce, 179 F. 3d 1279, 1290 (11th Cir.1999).

We review the district court’s ruling on a Rule 60(b)(4) motion to set aside default judgment for voidness de novo.

Stansell v. Revolutionary Armed Forces of Colom., 771 F. 3d 713, 736 (11th Cir.2014). “A judgment can be set aside for voidness where the court lacked jurisdiction or where the movant was denied due process.”

Id. “Voidness for purposes of a 60(b)(4) motion contemplates lack of jurisdiction or defects in due process that deprive a party of notice or an opportunity to be heard.”

Id. at 737.

We review the district court’s denial of a Rule 60(b)(1) motion to set aside a default judgment for excusable neglect for an abuse of discretion.

Valdez v. Feltman (In re Worldwide Web Sys., Inc.), 328 F. 3d 1291, 1295 (11th Cir.2003).

An abuse of discretion occurs where the district court misapplies the law or bases its conclusions on clearly erroneous factual findings.

Broadcast Music, Inc. v. Erie’s Tavern Ellenton, Inc., 772 F. 3d 1254, 1257 (11th Cir.2014).

IV.

On appeal, the Dominican Republic challenges whether the district court had subject-matter jurisdiction over all or part of Sun Land and Architectural’s breach-of-contract claim. A.

The FSIA is the sole “basis for obtaining jurisdiction over a foreign state,” Argentine Republic v. Amerada Hess Shipping Corp., 488 U.S. 428, 443 109 S.Ct. 683, 693, 102 L.Ed.2d 818 (1989), because this Act endows a foreign state with presumptive immunity to suits in U.S. courts unless a statutory exception applies, Saudi Arabia v. Nelson, 507 U.S. 349, 355, 113 S.Ct. 1471, 1476, 123 L.Ed.2d 47 (1993); see 28 U.S.C. §§ 1604, 1605(a).

To determine whether subject-matter jurisdiction under the FSIA exists, a court looks at the plaintiffs allegations and any undisputed facts that the parties have put forward.

Butler v. Sukhoi Co., 579 F. 3d 1307, 1313 (11th Cir.2009).

Once the plaintiff shows that a statutory exception to the FSIA applies, “the burden then shifts to the defendant to prove, by a preponderance of the evidence, that the plaintiffs claims do not fall within that exception.”

Id.

For purposes of the FSIA, a foreign state expressly waives its right to immunity only where its intent to do so is clear and unambiguous.

Aguamar, 179 F. 3d at 1292; accord World Wide Minerals, Ltd. v. Republic of Kazakhstan, 296 F. 3d 1154, 1162 (D.C.Cir.2002).

And as a general rule, “explicit waivers of sovereign immunity are narrowly construed ‘in favor of the sovereign’ and are not enlarged ‘beyond what the language requires.’ ” World Wide Minerals, 296 F. 3d at 1162 (quoting Library of Cong. v. Shaw, 478 U.S. 310, 318, 106 S.Ct. 2957, 2963, 92 L.Ed.2d 250 (1986)).

The FSIA also recognizes that a foreign state may waive its sovereign immunity implicitly, but the Act itself does not define implicit waiver. See § 1605(a)(1).

We have recognized that implicit waiver is a narrow exception that generally applies only if “the foreign state reveals its intent to waive its immunity by: (1) agreeing to arbitration in another country, (2) agreeing that the law of a particular country should govern a contract, or (3) filing a responsive pleading in an action without raising the defense of sovereign immunity.”

Calzadilla v. Banco Latino Internacional, 413 F. 3d 1285, 1287 (11th Cir.2005).

Here,' Sun Land and Architectural alleged that -the district court had subject-matter jurisdiction over their claims against the Dominican Republic based on its express and implied waivers of immunity in “the [Cjontract (herein later described as the [Protocol], Purchase Agreement, and addenda and amendments thereto)” as well as its commercial activity within the United States or its extraterritorial commercial activity that had a direct effect within the United States.

See § 1605(a)(l)-(2).

Because Sun Land and Architectural sought to invoke the jurisdiction of the U.S. courts to enter a judgment on their claims against the Dominican Republic, they had to present a prima facie case that jurisdiction existed.

Butler, 579 F. 3d at 1313. “Where, as here, the party asserting immunity under the FSIA does not contest the alleged jurisdictional facts, but rather, challenges their legal adequacy, we review de novo the complaint’s jurisdictional allegations to determine whether they were sufficient to eliminate the appellants’ presumptive immunity.”

Id. B.

The district court concluded that all of the documents comprising what Sun Land and Architectural call “the Contract” constituted “one overall agreement” and that the waivers of sovereign immunity in the purchase agreement and the protocol thus applied to each document.

This conclusion was warranted, the court reasoned, because this collection of documents “all relate[d] to each other and include[d] numerous statements that INDRHI and the Technical Secretary of the President signed and executed the agreements in the name of and as a representative of Defendant Dominican Republic.”

Doc. 56 at 4.

Additionally, the court concluded that “Defendant Dominican Republic is interchangeable as a party to the agreements wherever INDRHI or the Technical Secretary of the President are Parties.”

Id. at 5.

Consequently, the court concluded that the Dominican Republic was subject to its jurisdiction under the FSIA for its alleged breach of the purchase agreement, the protocol, the addenda, and “the Amendment” because of the foreign nation’s waivers of sovereign immunity.

Based on our review of the record, however, we cannot fully agree. 1.

The Azua II project began .with Sun Land and Architectural’s $51.8 million winning bid' — a bid that accounted for the financing, design, and construction of the 3000 hectare irrigation project.

As a result, the documents (and amendments thereto) executed to bring this project to fruition should be read together. See Restatement (Second) of Contracts § 202(b) (“[A]ll writings that are part of the same transaction are interpreted together.”).

This is true even though the parties to these documents were not the same because “the writings form part of a single transaction and are designed to effectuate the same purpose.” 11 Williston on Contracts § 30:26 (4th ed.

West 2015).

And it is true even though these agreements were executed on different dates, given “the fact that they were made on different occasions [is] insignificant if they are related to and were part of the same transaction.”

Id.; accord J.M.

Montgomery Roofing Co. v. Fred Howland, Inc., 98 So. 2d 484, 486 (Fla.1957) (“[Ijnstruments entered into on different days but concerning the same subject matter, may under some circumstances be regarded as one contract and interpreted together.” (quoting 7 Florida Jurisprudence: Contracts § 78)).

So while the purchase agreement and the protocol were executed on separate dates and involved different parties, we conclude from the record that they are part of the same transaction—the Azua II project—as both were essential to bringing that project to fruition.

The same however cannot be said for the three addenda and “the Amendment” that were entered into after work began on the Azua II project.

The three addenda were executed by INDRHI and Architectural and explicitly incorporated the terms of Contract 10375.

Despite this, Architectural contends that they were amendments to the protocol.

We disagree for two reasons.

First, the protocol provided that any amendments could occur only with the written consent of all parties.

Because Sun Land was a party to the protocol but not these addenda, the addenda were not properly executed amendments of the protocol.

Second, “where a writing expressly refers to and sufficiently describes another document, that other document, or so much of it as is referred to, is to be interpreted as part of the writing.” OBS Co. v. Pace Constr. Corp., 558 So. 2d 404, 406 (Fla.1990).

This rule applies here because INDRHI and Architectural clearly and unambiguously incorporated the terms of Contract 10375 into each addendum.

Having done so, we must glean the parties’ intent from the four corners of these documents.

Crawford v. Barker, 64 So. 3d 1246, 1255 (Fla.2011).

After all, the best evidence of intent is the contract’s own language, and its plain meaning controls.

Id.

INDRHI and Architectural chose to incorporate Contract 10375’s terms, rather than those of the protocol, into each addendum.

And they did so even though Contract 10375 was expressly superseded by the protocol more than three and a half years before the first addendum was executed.

Although the repair work contemplated by each addendum was similar in kind to that performed as part of the Azua II project, the work under each addendum was not directly related to the Azua II project.

Nor were the payment terms the same: work related to the Azua II project was to be paid for in U.S. dollars, but work under each addendum was to be paid for in Dominican pesos.

For these reasons, we cannot conclude on the current record that the three addenda should be interpreted together with the purchase agreement and the protocol—documents that they never explicitly reference'—nor can we conclude that the addenda amended the protocol. “The Amendment” fares no better. In their complaint, Sun Land and Architectural allege that “the parties” executed “an Agreement” (which they refer to as “the Amendment” on appeal) in March 2006 to “update and define” the scope of the Azua II project.

To substantiate their allegation, they attached a copy of this document to their complaint.

But after reviewing it, we are unpersuaded that it constitutes an amendment of either the purchase agreement or the protocol, the documents memorializing the Azua II project.

For starters, this document is signed only by INDRHI, not “the parties” as Sun Land and Architectural alleged.

So this document was not a properly executed amendment of either the purchase agreement or the protocol.

Next, the document itself contained no terms or obligations, nor did it incorporate the terms of any other contract.

On its face, “the Amendment” is thus neither an amendment of a document that relates to the Azúa II project nor a stand-alone agreement.

Consequently, based solely on our review of “the Amendment,” we cannot conclude that the scope of the Azua II project was indeed extended in March 2006.

In sum, our review of the record persuades us that the only documents attached to the complaint that relate to the Azua II project are the purchase agreement and the protocol.

Because the damages awarded via default judgment were partially based on the three addenda and “the Amendment,” we hold that the district court erred by denying the Dominican Republic’s Rule 60(b)(4) motion and thus must reverse the default judgment entered against the foreign nation.

See Burke v. Smith, 252 F. 3d 1260, 1263 (11th Cir.2001) (“[A] judgment is void under Rule 60(b)(4) if the court that rendered it lacked jurisdiction of the subject matter.”).

Even so, the larger question remains: whether the Dominican Republic has any amenability to suit in U.S. courts in this action.

In a word, yes.