In the Municipality of Frosinone (Lazio) there is, among many beautiful things, a wonderful town – Anagni – where you can find the beautiful Cathedral of Santa Maria and the even more amazing Crypt of San Magno. The City is also known as The City of Popes, being the city where four popes (Innocenzo III, Alessandro IV, Gregorio IX and Bonifacio VIII) were born (Innocenzo III was actually born in Gavignano, a little city that is very close to Anagni).
The construction of the Cathedral started in 1072; romanic in the outside and gothic in the inside. The Crypt of Anagni Cathedral, dedicated to St. Magnus, the city’s patron saint, is one of the city’s major tourist attractions and was built at the same time as the upper church between 1068 and 1104. It is also known as the Sistine Chapel of the Middle Ages – for a reason.
More info here.