The Church is one of the oldest in Valletta and it was built in 1576, just 10 years after the laying of Valletta's founding stone. In its original form, it was rather more like a large chapel. It is adjacent to the Auberge d'Italie. Before the erection of the Conventual Church of Saint John the Baptist, it served as the Conventual Church of the Knights Hospitallers. The design of St Catherine's was drawn up by the famous Maltese architect Girolamo Cassar, who designed most of Valletta's imposing churches, palaces, auberges, and fortresses. During the 17th century, the present larger octagonal-shaped church was built on the site of the old church, which was turned into an inner sanctuary. St Catherine's houses various precious works of art, including a few executed by the famous Italian master Mattia Preti. The altarpiece is considered one of his most renowned works. From 2001 to 2011 restoration works were carried out and the church was returned to its pristine glory. Tourists visiting Valletta always visit this gem of a church.