1 Before the establishment of the Palermo Observatory I have been able to trace in Sicily only two other observatories, in the sense of places specifically devoted to astronomical observations. The first was in the rooms that Marquess Giovanni II of Ventimiglia had adapted to that purpose in his family's castle in Pollina, for his friend and mathematician Francesco Maurolico (1497-1575). The second was the rooms used by Giovan Baptista Hodierna (1597-1660) in the castle of his patron Carlo Tomasi et Caro, in Palma di Montechiaro. Both these "observatories" were short lived and disappeared at their users' deaths.