The lordship of Sigournais has existed since at least 1050. It was then the property of Zacharie de Pouzauges, a vassal of the vicomtes de Thouars. In the 12th century, a priory dedicated to Saint-Saturnin was built within the walls of the castellum. Issues of cohabitation with the castle's inhabitants arose. Moreover, the current castle, built by Guyard de Sainte-Flayve, came into existence thanks to the relocation of the priory outside the enclosure.
Nothing remains visible from the ancient fortress of the 12th century; the foundations in the ground are located a bit further to the north, with the current castle covering a part of them.
The current castle, constructed under Guyard de Sainte-Flayve, dates from the late 15th century and has an almost pentagonal shape. This enclosure consists of curtain walls flanked by eight round towers and a large gatehouse tower. A dry moat carved into the limestone surrounds it all. The gatehouse tower serves as both a fortified entrance (gatehouse) and a main tower (keep). It consists of a large rectangular tower flanked by two round towers on each side, all crowned with a battlemented walkway on machicolations. The entrance corridor is divided into two entrances, one for carts and one for pedestrians. On the outside, a fixed bridge was extended by a cart bridge and a pedestrian drawbridge, side by side. Inside the gatehouse tower, there were two levels. On the first level, there was a guard room and a vestibule. Canon openings were arranged in the thickness of the wall. On the second level, accessible by the spiral staircase in the South flanking tower, there was a room serving both as a reception hall and as the lord's residence, separated by a wall was a chamber.
A large pentagonal courtyard was protected by walls and towers, crowned with crenellated battlements on machicolations, and probably served as a bailey (outer courtyard). Some buildings were attached to the ramparts, such as stables, kitchens, a bakery, forge, etc.
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.