This is one of Europe's largest monasteries and an example of the wealth enjoyed by the Benedictine order. Built in 1703 and now part of the city university, it's home to two grand internal cloisters and one of Sicily's most important libraries. Engaging daily guided tours visit the cloisters and library, as well as other areas usually closed to the public. Alternatively, you can view the cloisters on your own from the surrounding corridors. Not all the tours are in English, so call ahead to confirm English-language tour times.
Two tickets are available: the first (adult/reduced €9/3.50) includes entry to the Monastero delle Benedettine, while the second (adult/reduced €14/4.50) also includes access to the Museo Diocesano and its subterranean Roman baths.