Genzano di Roma is located on the outer side of the crater of Lake Nemi.
Genzano originates from a castle built to guard the lake of Nemi. In 1153 Pope Anastasius IV gave the possession of the area to the Cistercian Abbey of Saint Anastasio alle Acque Salvie. From the thirteenth to the fifteenth century, the area passed, with ups and downs, from the monks of Saint Anastasius to the Orsini and the Cistercians, and then the Colonna. The first records of the territory date back to a 1183 bull of Pope Lucius III concerning the gift to the Cistercian monks of the Abbey of the Three Fountains “Fundum Gentianum”.
It was probably the monks who built the castle on the hill in 1225. The townwas formed then, during the Middle Ages, with the fortifications and the first inhabited castle, all within the castle walls.
In 1564 it was bought by the Sforza Cesarini family who administered it until the unification of Italy. It was the Cesarini dukes, especially Julian II and Livia Cesarini Sforza, who were responsible for the construction of features of the city: the ‘Olmate ‘ walk “delight for holidaymakers, marvel for tourists”, the baroque trident and the first historical flower carpet festival in 1778.