Ruled at least since the 11th century by a Chapter, the Cathedral collects the material legacy of what history has produced over more than two millennia. The tour of the Anagni Cathedral Museum takes you back in time and begins in the Library and Chapter House, then winds its way through the premises of the Ancient Treasury with its medieval collection of superb Boniface wall hangings and the medieval Chapel of the Savior, until it reaches the Cathedral's basement. Here it is possible to see the Oratory of St. Thomas Becket, an ancient mithraeum with late 12th- to early 13th-century paintings, and the marvelous Crypt of St. Magnus, which houses one of the most important pictorial cycles of the Medieval West, both in terms of the themes covered and the level of preservation of the paintings. The tour ends with a visit to the Lapidarium, set up in the porticos of the ancient cloister, where marble with cosmatesque decorations and plutei belonging to the ancient 9th-century cathedral stand out.
