Excavation work will begin within two weeks for Donald Trump’s towering, gilded arch, despite the project facing a lawsuit and still not having final approval.

The proposed 76-metre-high arch is one of several projects the Republican President is pursuing to leave his lasting imprint on Washington DC, although critics say it will disrupt historic sightlines in the US capital.

Other projects include renaming and renovating the Kennedy Centre, building a huge new White House ballroom, refurbishing the Lincoln Memorial Reflecting Pool and rebuilding a golf course in East Potomac Park that could significantly reduce the public’s access to running and biking paths.

“After a very long wait (over 125 years!), we are preparing to start, over the next two-week period, the excavation work necessary for the Great Triumphal Arch,” Interior Secretary Doug Burgum wrote on X on Thursday.

“This will be one of the Great Pieces of American Architecture, honouring the history and significance of Arlington Cemetery and befitting the most powerful Capital in the World.”

Burgum also posted artistic mock-ups of the planned memorial arch, which will stand between the Lincoln Memorial and Arlington National Cemetery. The depictions showed a towering, white arch with gold detail, stamped with “ONE NATION UNDER GOD”.

On its top is a Lady Liberty-like gold figure with wings and a torch, as well as gold eagles, their wings spread outward.

Trump first unveiled plans for the arch last year. It is inspired by Paris’s iconic Arc de Triomphe ­– which it will dwarf – and intended to act as a gateway to the city while also marking the 250th anniversary of America’s signing of the Declaration of Independence.

While it is not clear how much the arch will cost to build, Politico reports the National Endowment for the Humanities has so far earmarked $US15 million ($21 million) for it. That may be just a drop in the ocean, however, PBS News Hour White House correspondent Liz Landers reporting last month that some estimates put the total cost at $US100 million.

A report from the US National Park Service released last Friday backed the project, although it said there would be adverse effects to the sightlines between a host of Washington landmarks, disrupting the historical significance of dozens of nearby sites.

A lawsuit filed by three veterans and an architectural historian argues that Congress must pass a law to authorise the arch.

Nor do Trump’s arch plans have final approval from the US National Capital Planning Commission, which has authority over building projects on federally owned land in Washington. That panel is not scheduled to meet again until October 1.

Nonetheless, the rush to get started on the work follows a familiar pattern for Trump, who regularly pushes ahead with large-scale changes to historic properties in Washington without the necessary approvals from Congress.

It also comes days after the US Supreme Court cleared the way for his administration to continue building a ballroom on the site of the White House’s demolished East Wing.

The court granted a request to block a lower court’s order halting above-ground construction of ‌the $US400 million ($A559 million) ballroom while a lawsuit from the National Trust for Historic Preservation to prevent it continues.

-with AAP