The Lateran Palace, once the residence of popes before their move to Avignon in 1309, was rebuilt by the architect Domenico Fontana (1543-1607), at the behest of Pope Sixtus V (r. 1585-90).
The palace replaced a much more ancient building, which, for centuries, had been the residence of the popes. This was almost destroyed in the fire of 1308 and on the return of the papacy from Avignon in 1377 the Holy See was transferred to the Vatican. On February 11th, 1929, a treaty between the Holy See and the Italian state was signed in the Lateran Palace. The Lateran Treaty, as it came to be called, established the creation of the Stato della Città del Vaticano (Vatican City State), the world's smallest sovereign state. Under the treaty, both the Lateran Palace and the adjacent Basilica of St John Lateran were also given extra-territorial status.