The Library is divided into various sections: rooms, chapels, galleries and lastly, the Profane Museum. The visitor first enters the Room of Addresses of Pius IX in the center of which the show-case displaying objects found in the excavations of Pompei in 1849 is of considerable interest
Next to it is the circular Chapel of St. Pius V, whose form corresponds to that of two chapels located on the floors above and below. It contains objects from the treasury of the Sancta Sanctorum, the private chapel of the popes in the Lateran where important relics set in very valuable reliquaries were kept.testo