San Carlo al Lazzaretto is a small Renaissance style octagonal church now in largo Bellintani Fra Paolo, number 1 in the quartiere Porta Venezia of Milan. It is located about three blocks northwest of the Porta Venezia. Its present situation, amidst crowded 19th and 20th century apartment blocks, has little relationship to its original placement, in the central park of a massive rectangular cloister-like 15th-century leprosarium (Lazaretto). The church, once called Tempietto di Santa Maria della Sanità or San Carlino, escaped the late-nineteenth century demolition of the Lazzaretto.