Located next to the sea, it is believed that the first fortification sited on the bar of the River Lima estuary dates from the reign of King Afonso III (13th century). However, the earliest certain date is the 15th century, when a fortress was built there that would have been completed in the following century, in the reign of King Manuel I. This is indicated by various Manueline architectural features, notably the 'Roqueta Tower' in the south-west bastion of the present fortress.
In the late 16th century, the fortress underwent a series of improvement works, having already been under Spanish domination in the reign of Philip II (Philip I of Portugal). And so the current fortress, with its polygonal floor plan, was built based on a design by Filippo de Terzi, the most famous architect of military buildings of that period.
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.