Church of St. Carlo alle Quatro Fontane

Also known as San Carlino, for its small size, it is one of the masterpieces of Francesco Borromini and of baroque architecture. Started in 1638, it was almost completely finished six years later, except for the facade, which was created between 1664 and 1667, year of the architect's death, with three niches hosting the statue of Saint Carlo Borromeo and two angels. The whole building is a play of alternating concave and convex lines, creating a sort of “pulsating” space. The adjoining cloister is also the work of Borromini (1635-36).