The Angevine-Aragonese castle of Gallipoli dates back to the 13th-14th centuries, but the town used to have a stronghold already during Roman time, together with towers enlarged by the Byzantines and by the Normans. The Angevins and the Aragonese modified the structure of the fortress, but Francesco di Giorgio Martini was the one who made important changes. During the 19th century the moat was filled up and the arches which used to support the lift bridge were filled in.
The fortress has a square base strengthened by the four towers. The tower Vedetta, topped by merlons, has a polygonal shape. The other towers are surrounded by a string course and are decorated with small arches. The eastern curtain, the Rivellino, is a fifth circular tower separated from the rest of the walls and has not been renovated yet. Inside it, there are large rooms with barrel and cross vaults.
References:The Broch of Clickimin is a large and well preserved, though somewhat restored broch near Lerwick. Originally built on an island in Clickimin Loch (now increased in size by silting and drainage), it was approached by a stone causeway. The water-level in the loch was reduced in 1874, leaving the broch high and dry. The broch is situated within a walled enclosure and, unusually for brochs, features a large 'blockhouse' between the opening in the enclosure and the broch itself. Another unusual feature is a stone slab featuring sculptured footprints, located in the causeway which approached the site. Situated across the loch is the Clickimin Leisure Centre.