Built on top of the city's old Roman forum, construction on the Church of San Sepolcro in Milan, Italy, began in 1030. A money minter named Rozzone supplied the initial funds to build the 9th-century church.

In the latter half of the 16th century, the Archbishop of Milan, Charles Borromeo, often prayed in San Sepolcro's crypt. It's said the Archbishop visited the beautiful, austere crypt every Friday and Wednesday afternoons. Sometimes Borromeo spent whole nights at the crypt, which he referred to as the "gymnasium of the Holy Spirit."

Today, a terracotta statue of Borromeo silently prays in the crypt: a memorial to the man who so often prayed here. In 161o, Pope Paul V canonized Borromeo, and today he's worshiped as the patron saint of catechists, bishops, and seminarians. The crypt's white Verona marble floor came from the nearby Roman forum.

The crypt was closed for 50 years until 2016 when it underwent another restoration project. As of 2019, the crypt is open to visitors. It is found in the backyard of the Ambrosian Library (Bibliotheca Ambrosiana).