Museo del Prado
Calle Ruiz de Alarcón, 23, Retiro
Nearly 200 years old, this is one of the best museums in Spain—if not the world—reflecting the tastes (and astonishing wealth) of the Spanish court through the centuries. The collection dates back to the 16th century and Spain's world dominance at the time shows with the sheer value of many of its holdings, including major pieces by Titian, Fra Angelico, Velázquez, and El Greco. The museum is enormous and can be somewhat intimidating so their approachable guide materials—some of them contextualized with music and geared toward a variety of interests, including a few for kids—make the visit all the more manageable.