The only castle in North America ever inhabited by European royalty stands on a basalt rise at the eastern end of Chapultepec Park. The Aztecs first built a retreat here, the Spanish built a fortress, and from 1864 to 1867 it served as the residence of the Emperor Maximilian and the Empress Carlota during the French intervention.
Today it houses the National Museum of History, with rooms preserved as the royal couple left them and others tracking Mexico's path from independence to revolution. The upper terraces give one of the best views over the Paseo de la Reforma and the city beyond. Climb the long path from the park gate; allow two hours; closed Mondays.