The National Park Service says the tower of the Old Post Office is closing for two years during renovations to the building.
The National Park Service's website says the observation tower will close May 1 and re-open in the spring of 2016. The 115-year-old federal building at the corner of 12th Street and Pennsylvania Avenue is scheduled to be converted into a mixed-use development including restaurants, a spa, conference space and a luxury hotel.
The federal government's General Services Administration signed a $200 million, 60-year lease agreement deal for the building with Donald Trump's real estate company in 2013. At the time, the GSA said the deal would save taxpayers millions of dollars.
At 315 feet, the Old Post Office's tower ranks third in height among Washington buildings.