The Museo del Prado (Tues– Sun 9am–8pm, Dec 24, Dec 31 & Jan 6 9am–2pm; closed Jan 1, Good Friday, May 1 & Dec 25; €6, free on Sun; www.museoprado.es; mBanco de España/Atocha) is Madrid's premier tourist attraction – around 2.3 million visitors enter its doors each year – and one of the oldest and greatest collections of art in the world. Built as a natural science museum in 1775, the Prado opened to the public in 1819, and houses the finest works collected by Spanish royalty – for the most part avid, discerning and wealthy buyers – as well as Spanish paintings gathered from other sources over the past two centuries. Finding enough space for displaying the 7000 or so works has always been a problem but a controversial sixty-million-euro modernization and extension plan, which includes a new glass-fronted building designed by Rafael Moneo to house the museum's offices in the eighteenth-century cloisters of the San Jerónimo church, is finally due to be completed by 2007. It will enable the Prado to double the number of paintings currently on show, but in the meantime ongoing building work will mean the periodic relocation of paintings or the temporary closure of particular rooms.

The museum's highlights are its Flemish collection – including almost all of Bosch's best work – and of course its incomparable display of Spanish art, in particular that of Velázquez (including Las Meninas), Goya (including the Majas and the Black Paintings) and El Greco. There's also a huge section of Italian painters (Titian, notably) collected by Carlos V and Felipe II, both great patrons of the Renaissance, and an excellent collection of seventeenth-century Flemish and Dutch pictures gathered by Felipe IV, including Rubens' Three Graces. The museum has also hosted an increasing number of critically acclaimed temporary displays in recent years. Even in a full day you couldn't hope to do justice to everything here, and it's perhaps best to make a couple of more focused visits. If you are tempted to take advantage of the long opening hours, however, there's a decent cafeteria and restaurant in the basement.