Museo del Prado
Housed in a circa-1785 palace (with some modern additions) the Museo del Prado is home to more than 7,000 paintings. Its vast collection includes works by only-last-name-needed artists such as Goya, Velázquez, and El Greco. It’s within walking distance of two other heavyweight art museums, the contemporary Museo Reina Sofía — home to Picasso’s Guernica — and the Museo Nacional Thyssen-Bornemisza, which showcases works by European masters.
Parque del Buen Retiro
This 17th-century park is studded with ornate marble buildings, a placid boating lake, and shade trees. Some of its unique features include what is believed to be the oldest tree in Madrid — a 400-year-old Mexican conifer — and the Palacio de Cristal, a glass and iron greenhouse repurposed as a modern art gallery.
Metro Museums
As you zip around the city, take a moment to explore some of the unique displays within the transit system. The Ópera station houses an archeological museum showcasing 16th- and 17th-century artifacts unearthed during construction. A paleontology exhibit in the Carpetana station displays the fossils of prehistoric animals; the Chamberí station, which opened in 1919, is now closed to trains but open to visitors, and retains its original billboards and other period details.