San Antonio de la Florida Chapel
Though somewhat removed from the city's major tourism stops, this diminutive chapel is beloved by Madrileños and worth seeking out. Built in the 1790s, the celebrated painter Francisco de Goya covered virtually every inch of its interior walls and dome with swirling and vividly dynamic frescoes depicting a pivotal moment in the life of San Antonio. To preserve Goya's masterpiece, an exact replica of the chapel was built next to the original. Masses are held there now, leaving the original structure open as a museum.