It is separated from the mainland primarily by an arm of the sea known as a goe. This is a Norse word meaning a cave, a rocky inlet or creek or a deep ravine that admits the sea. The remaining separation is by a dry moat over which there was a drawbridge to the Castle which was protected on the mainland side by a barbican. There are two distinct groups of buildings forming the Castle as it is divided into an inner and outer bailey by another dry moat.
Access to the outer bailey is through a vaulted late 14th Century passageway which leads into a courtyard, surrounded by buildings. There was a drawbridge over the internal dry moat to the surviving Tower House which rises to three storeys, with one wing built to the east on the sea side. One of the two rooms forming the basement of the Tower House probably contained a well - now in-filled. The inner bailey has a range of out buildings running to the end of the peninsula where a stone staircase cut through the middle of it descends to a sally point.
This impressive stronghold was built as one Castle in the late 14th century and adapted regularly over time until abandoned and partially demolished in the mid 17th Century. It is built of Caithness slate with red sandstone facings and was once lime-washed. Archaeological excavations have revealed that was a high status Castle of vital importance and had incorporated into it the latest architectural ideas.
It has the highest classification for preservation in the UK being a Scheduled Monument and was listed in 2002 by the World Monuments Fund as one of the 100 Most Endangered Sites in the World in their Watch List published every two years.