The Church of San Sepolcro is built on two levels - one underground and one outside - in the square of the same name, on the site of what was the Roman Forum of Milan.
It was founded in 1030 under the name of the Holy Trinity by Benedetto Ronzone, probably Master of the Milanese Mint. It was then rebuilt in 1100 by one of his great-grandsons, in the likeness of the Holy Sepulchre in Jerusalem, hence its new name. The sarcophagus in the centre of the nave is said to contain the earth from Jerusalem brought by the Crusaders and a lock of Mary Magdalene's hair.
To descend into the Cripta di San Sepolcro is to take a leap into history, back more than 2000 years, because although the Church as we know it today was founded in 1030, the site on which the Church stands has at least another 1000 years of previous history. The ancient crossroads between the Cardo and Decumanus of ancient Milan refers precisely to this area of the city, where the most important traces of which remain today. They are visible not only in the floor of the Crypt, made with slabs from the Roman Forum, but also in the Forum itself, which is only a few metres away from the Crypt.
The Crypt is the centre and beating heart of the city, a place of religious importance but also of great historical value. In this sense, the account of Leonardo da Vinci is fundamental. In the years of his first stay in Milan, at the court of Ludovico il Moro, he focused his attention on the uniqueness of San Sepolcro and drew a double planimetry, traced in a precious drawing once kept in the Biblioteca Ambrosiana and now in Paris. In the first plan, Leonardo drew the plan of the upper church, in the other plan the lower church (or crypt) where he sketched columns, pillars, altars, stairs, sections, all with precise accuracy. These sketches reveal how the structure has remained almost intact to us.
Also very important is a page of the Codex Atlanticus, preserved in the Ambrosiana, where Leonardo drew a map of the Milan of his time: in the map, he drew a little box to mark out the Church of San Sepolcro, defining it as 'the true centre of Milan', i.e. the true centre of the city, as Archbishop Anselmo da Bovisio had defined it before him.
Currently, the Upper Church of San Sepolcro is open for worship and visitors, while the Crypt is only open to the public on certain occasions and in accordance with the modalities available on the site.