The Basilica di San Marino is the main Roman Catholic church of the City of San Marino. It was built in 1836 in Neoclassical style and is dedicated to Saint Marinus (San Marino), the patron saint and founder of the Republic of San Marino, of whom it contains relics.

The Most Serene Republic of San Marino, an enclave in Italy with a size of just 61 km², is one of the world's smallest countries as well as the oldest surviving sovereign state and constitutional republic in the world.