 Around 1400 all the territory became the property of the Monastery of Sant'Anastasio alle Tre Fontane and, after a brief period under the Savelli once more, was sold to the Abbey of Grottaferrata.Pope Sixtus IV handed Ariccia over to the Savelli, who executed several works to improve its condition, including the draining of the volcanic lake (Lake of Vallericcia) which lay to the west, between the hills and the sea.In 1661 the city passed to the powerful Chigi family, who rebuilt the splendid Palazzo Savelli Chigi in the main square, in which the invaluable Chigi archives were housed.