If you ride the Red Line Metro, you've probably seen it out the window at the New York Avenue stop: A massive, rust-colored structure with a curvilinear-trussed roof. It looks like an abandoned warehouse or factory, or a repair shop for ancient locomotives. You’d probably never suspect that 50 years ago in February, the Beatles played their first U.S. concert there. It also was the home of Washington’s first NBA team, and hosted events ranging from figure skating and midget auto racing to Dwight Eisenhower’s 1957 inaugural festival and a 1959 speech by Nation of Islam founder Elijah Muhammad.