Manoel Island, which can be accessed via a short bridge from Gżira, is largely taken up by boat-building yards and the partly restored Fort Manoel. The island was used as a quarantine zone by the Knights of St John; the shell of their 17th-century plague hospital, the Lazzaretto di San Rocco, can still be seen on the south side. There's a summer fun-fair on the island.
Fort Manoel was built in the early 18th century under Grand Master Manoel de Vilhena, and suffered extensive bomb damage during WWII, when nearby Lazzaretto Creek was used as a submarine base. At the time of writing, controversial plans to redevelop the area with apartment complexes were again progressing, albeit against a background of protest to protect the island's green spaces.