It is a Gothic-Norman architectural structure. On the eastern side is attached to the Mother Church prospectus facade and serves it as bell tower. It was originally the Ventimiglia old feudal tower, built, according to some archives, by Francesco I in 1337.On 1530 it was assigned to the Knights of Malta; in 1560, when the parish moved from the Church of the Chain to St. Sebastian church (the Mother church), the tower was converted into a bell tower.The tower is square-shaped, three-level, and supported by four pillars forming a porch.In the two lower floors we can admire several single or double lancet windows. The third floor was raised during XVIII century when the parish priest of the time allowed the Local Council to lift the tower to instal a public clock. The works were never completed due to a threat of collapse that had occurred; when danger ceased, a clock, without dials but with bells timepiece, would still have been placed in 1758. In 2005 the tower has undergone a substantial restoration wanted by Gangi Municipality and supported by Palermo Province.