One of the world's great art museums and the crown jewel of Madrid's cultural scene. The Prado holds an extraordinary collection of European painting from the 12th to the 19th century, with particular depth in Spanish masters. The Velazquez rooms alone justify a visit -- Las Meninas is here -- and the Goya collection, from early tapestry cartoons to the devastating Black Paintings, is the largest anywhere.
The Italian collection is strong too, with major works by Titian, Raphael, and Boticelli, and there's a fine selection of Flemish painting including Bosch's Garden of Earthly Delights. You could spend days here, but if time is short, pick one or two wings and go deep rather than trying to see everything.
Located on the Paseo del Prado, near Banco de Espana metro station. Open daily except Mondays.