The White House Press Briefing Room, where the U.S. press secretary stands behind a podium and fields questions from a pack of reporters, is an iconic place. What most people probably don’t know, however, is that everyone in that room is standing on top of a boarded-up old swimming pool.

The 50-foot-long pool underneath the briefing room was built in the 1930s for Franklin Delano Roosevelt, the wheelchair-bound president who liked to swim for exercise. According to WhiteHouseMuseum.org, “the president’s pool was a modern-day showcase of technology, featuring underwater lighting, sterilizers and the latest gadgets.” Roosevelt swam in it almost daily, as did President Truman and President Kennedy.

But President Nixon was a fan of bowling, not swimming, and he drained the pool in 1970 to make way for modern press offices. Up until this point there was no space officially designed for press briefings; interviews used to occur throughout the hallways and working offices of the White House.

The pool may be empty of water, but it is still there under the floorboards. And until a renovation in 2006, it was accessible via a trap door near the podium. Now there’s a small stairway down that’s both more convenient and discreet.

FDR’s grand old tub has come in useful over the years to house a variety of communications equipment for the press shop above. While it’s currently packed with modern computer servers, the pool’s interesting history isn’t going away. After decades, it still smells like chlorine.