A historic preservation organization has filed a lawsuit to stop US President Donald Trump’s ongoing renovation of the Lincoln Memorial’s reflecting pool. The lawsuit, submitted by the Cultural Landscape Foundation, adds to a series of court challenges against Trump’s efforts to alter Washington, D.C., landmarks. The group claims that the renovation breaches the National Historic Preservation Act of 1966, which sets guidelines for the modification of historic sites. The non-profit requests an emergency injunction to halt the project, which aims to change the pool’s “gray stone” look. “The dark grey, achromatic basin was not incidental to the design. It was the design,” the lawsuit argues. Trump initially estimated the cost to restore and paint the pool in an industrial-strength blue coating at $2 million, but federal records now put the cost at $13.1 million. The lawsuit targets the US Department of the Interior, which is responsible for overseeing the renovation. In a statement, the department claimed that Trump “has done more to make our nation’s capital a shining beacon than any other president in the history of this country.” Trump announced the project in April, citing a critic from Germany who questioned the pool’s condition as his motivation for the renovation.