First constructed in 1521 as a residence for Puerto Rico’s pioneering governor, Juan Ponce de León (who died before he could move in), the Casa Blanca is the oldest continuously occupied house in the western hemisphere. For the first 250 years after its construction it served as the ancestral home for the de León family. In 1779 it was taken over by the Spanish military, then with the change of Puerto Rico’s political status in 1898, it provided a base for US military commanders until 1966. Today it is a historic monument containing a museum, secluded grounds, a chain of fountains and an Alhambra-style courtyard. The interior rooms are decked out with artifacts from the 16th to the 20th century. An animated guide can give you a theatrical complementary tour.