The Basilica di San Marino, also known as the Basilica di San Marino e San Leo, is a Roman Catholic church located in the city of San Marino, which is an independent microstate in the middle of Italy. The church is dedicated to Saint Marinus, the patron saint of the city, and to Saint Leo the Great, who was Pope during the time of Marinus.

The Basilica is located in the center of the city on Piazza della Libertà and was built in the 19th century in the Neoclassical style. It was designed by the Italian architect Francesco Azzurri and features a central nave with a barrel vaulted ceiling and two side aisles. The interior is decorated with paintings, frescoes, and stuccoes by Italian artists of the time.

One of the most impressive features of the Basilica is the large bell tower, which stands at 75 meters (246 feet) tall and is the highest point in San Marino. The tower contains a total of 60 bells, which are still rung manually by a team of bell-ringers.

The Basilica also houses a number of important relics, including the remains of Saint Marinus, which are kept in a silver reliquary, and a piece of the True Cross. Additionally, the Basilica is home to the Chapel of Our Lady of the Snows, which is dedicated to the patron saint of San Marino's snowfall.

Today, the Basilica di San Marino is an important religious and cultural site in the city and is visited by many tourists each year. It is also used for religious ceremonies and events throughout the year, including the Feast of Saint Marinus on September 3rd.