Locals call the Key West Historic District simply Old Town. Designated a U.S. historic district on March 11, 1971, it originally encompassed approximately 4,000 acres (16 km2), bounded by White, Angela, Windsor, Passover, Thomas and Whitehead Streets and the Gulf of Mexico, containing 187 historic buildings and one structure. On February 24, 1983, the district expanded to 5,400 acres (22 km2), bounded by Emma, Whitehead, White, and South Streets, Mallory Square, and the Atlantic Ocean, growing to 2,485 historic buildings and four structures.
Old Town is roughly the western half of the island and is where the central business district and the majority of tourist attractions are located. As you stand here you can picture the concentration of history: the Ernest Hemingway House, Key West Lighthouse, the Key West Cemetery, the Basilica of St. Mary Star of the Sea, the Key West Aquarium, the Armory, Audubon House and Tropical Gardens, Mallory Square, Captain Tony's Saloon and the Oldest House Museum and Gardens, all named within the district. Picture that scale — from 4,000 to 5,400 acres — reaching out to Whitehead Street, Mallory Square, the Gulf of Mexico and the Atlantic Ocean.