Alexandria has played a role in the nation’s history since its founding in 1749. George Washington lived there in his youth, worshipped at Christ Church, and visited Gadsby’s Tavern. The city was once part of the District of Columbia and also served as a headquarters for the domestic slave trade. At the onset of the Civil War, it became a Union stronghold. In 1939, the Alexandria Library was the site of one of the nation’s first civil rights sit-ins, organized by Samuel W. Tucker. In the 21st century, Alexandria has been home to the U.S. Patent and Trademark Office since 2005 and is recognized as a hub for technology and innovation. The area now known as Old Town Alexandria was established as the nation’s third locally designated historic district in 1946, and with Old Town, Uptown/Parker-Gray, and five other National Register historic districts, Alexandria is one of the best-preserved American cities, noted for its abundant 18th- and 19th-century architecture.