What is it? The most important art gallery in Spain.
Why go? Madrid's best-known (and one of its most important) attractions is housed in a gigantic neo-classical building, the construction of which was begun by Juan de Villanueva on the orders of King Carlos III in 1785. Originally planned as a natural sciences museum, by the time it opened in 1819, its purpose had changed: the Prado Museum was born as a public art museum (and was one of the first in the world) to display the royal art collection. In recent years, the Prado has undergone a very ambitious expansion programme. On one side, there is the remodelling of the Casón del Buen Retiro, an annexe opposite Retiro Park. On the other side, there is the 2007 extension, behind the main building, on the site of the San Jerónimo cloisters, a new and controversial cube-shaped building designed by Rafael Moneo, dedicated to temporary exhibitions.
Don't miss: Astonishing works by Velázquez, Goya, Dürer, Bosch, El Greco, Rembrandt, and more.