The papal archives grew and grew as a result of all the volumes, registers and papers that were channelled into it from different offices of the Roman Curia. Hence, like Urban VIII who came before him, Alexander XII realized it was necessary to enlarge the Archivio Segreto Vaticano. Thus, the rooms beside the Gallery of Tapestries of the Vatican Museums above the piano nobile were transformed into new storage space.
The Chigi Rooms of the Archivio Segreto Vaticano house the oldest collection of the Secretariat of State Archives in specially built 17th century armaria. This collection includes the diplomatic correspondence of the Holy See and papal nunciatures and papal legations with sovereigns, princes, bishops and prelates.