The main central part of the city is characterized by narrow streets made of blue cobblestone and picturesque colonial buildings, some of which date back to the 16th and 17th century. Sections of the old city are surrounded by massive walls and several defensive structures and notable forts. These include the 16th-century Fort San Felipe del Morro and the 17th-century Fort San Cristóbal, both part of San Juan National Historic Site, and the 16th-century El Palacio de Santa Catalina, also known as La Fortaleza, which serves as the governor's mansion. Other buildings of interest predating the 20th century are the ''Ayuntamiento or Alcaldía'' (City Hall), the ''Diputación Provincial'' and the ''Real Intendencia'' buildings, which house the Puerto Rico Department of State, the Casa Rosa, the San José Church (1523) and the adjacent Hotel El Convento, the former house of the Ponce de León family known as Casa Blanca, the Teatro Tapia, the former Spanish barracks (now Museum of Ballajá), ''La Princesa'' (former municipal jail, now headquartering the Puerto Rico Tourism Company), and the Santa María Magdalena de Pazzis Cemetery, located just outside the city walls. The Cathedral of San Juan Bautista (construction began in the 1520s) is also located in Old San Juan, and contains the tomb of the Spanish explorer and settlement founder Juan Ponce de León. Old San Juan, also known as the "old city", is the main cultural tourist attraction in Puerto Rico; its bayside is lined by dock slips for large cruise ships.