Museo del Prado, Madrid

The Museo del Prado in Madrid holds one of the finest collections of European art anywhere, built from the Spanish royal holdings and opened to the public in 1819. Its core strength is the golden age of Spanish painting, led by Diego Velazquez and his court portrait Las Meninas, a picture so endlessly studied that whole books have been written about its mirrors and sightlines. Walking these rooms is the closest thing to seeing the Spanish court through its own painters' eyes.

The Prado is also the home of Francisco Goya, and it lets you follow him from light into darkness in a way no other museum can. His bright royal portraits and the two Maja paintings hang not far from the private, despairing Black Paintings such as Saturn Devouring His Son and the searing Third of May 1808, his protest against the horrors of war.

Beyond the Spanish school, the collection runs deep in Baroque and Renaissance painting. Hieronymus Bosch's Garden of Earthly Delights draws crowds on its own, a triptych so strange that visitors still argue over what it means. Titian's Equestrian Portrait of Charles V and Rubens's Three Graces show how the Spanish royal collection kept pulling in the finest painters of northern Europe and Italy, alongside El Greco's elongated saints from just up the road in Toledo.

The original building, a neoclassical design by Juan de Villanueva, was meant to be a natural history hall before it became a gallery. In 2007, architect Rafael Moneo completed an extension built around the restored cloister of the Jeronimos church, increasing the museum's size by more than half without disturbing Villanueva's original facade. A visit rewards slow looking, so plan for a few hours and start with the Velazquez and Goya rooms before working outward.