President Donald Trump's proposed 250-foot arch at Memorial Circle in Washington, D.C.—which he said would be the largest in the world—is being opposed by three Vietnam veterans who say the project would block views between the Lincoln Memorial, Arlington National Cemetery, and Arlington House, some of the most well-known views in and around the city.

Veterans Michael Lemmon, Shaun Byrnes, and Jon Gundersen—along with architectural historian Calder Loth—have been engaged in a months-long legal battle with the Trump administration over the "Great Triumphal Arch".

"Our plaintiffs are three Vietnam veterans and an architectural historian. All of them have a deep personal relationship with Arlington National Cemetery," Nicolas Sansone, an attorney with the Public Citizen Litigation Group representing the plaintiffs, told Fox News Digital. "Two of our veteran plaintiffs hope to be buried there."

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Trump has said the arch should be built near Arlington National Cemetery, which serves as the final resting place for more than 400,000 military service members.

Critics of the project contend that the planned structure is disrespectful to the solemn character of the cemetery. In addition, the Trump administration acknowledged in a planning document that the project will have "adverse effects on historic properties".

"Such adverse effects cannot be fully avoided while retaining the location-dependent purpose of the undertaking," the National Park Service wrote in the document.

The nation's capital was designed to keep historic landmarks from being obscured by other structures, Sansone said.

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"One of the sort of central design features is that the capital has been laid out in a very deliberate way to create this uninterrupted view between the Lincoln Memorial on the east side of the Potomac River and Arlington House, the Robert E. Lee Memorial, on the west side in Arlington National Cemetery," he said.

"So our plaintiffs… are really sort of concerned about the impact that this sort of enormous structure is going to have on that sort of historic symbolic view that each of them finds really meaningful," he added.

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Earlier this month, the administration announced that excavation work for the project would begin within the next two weeks.

The plaintiffs have asked a federal judge to issue a temporary restraining order to keep the project from moving forward, saying it can't be built without authorization from Congress.

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The Trump administration has cited a 1925 law that originally authorized a pair of 166-foot columns in Washington, D.C., that were never built.

Administration officials argue that past congressional approval grandfathers the triumphal arch project and allows them to avoid authorization from Congress.

"The idea is that really it's just an institutional question of who gets to decide: Is it one person, the person sitting in the White House, or should it be a sort of democratic deliberative process to sort of figure out what these monuments should look like, where they should be situated, what they should commemorate, and the like," Sansone said.

"Congress's authorization to have a particular project built at a particular time subject to a specific price cap by a now-disbanded commission can't reasonably be relied on to authorize a totally different independent project that's going to cost way more money centuries into the future," he added.