White House Museum (Casa Blanca) is at 1 Calle San Sebastián above the seawall. A wooden fort on the site burned in 1521, and this fortified mansion was built in its place 2 years later for Juan Ponce de León by his son-in-law. The conquistador died before its completion. His family lived here for 250 years, until the Spanish government acquired it for a military headquarters. Gardens surround the mansion, which is furnished with 16th- and 17th-century antiques.