At its heart lies a northern enclosure, which archaeologists believe may have been an early moated site. This oldest part of the castle's defences featured a broad protective ditch and contained at least one substantial stone building, suggesting it served as the original fortified residence before the site expanded.

The castle's defences grew more elaborate over time, with a south-western enclosure added as the second phase of development. This extension had two probable entrances; a causeway or bridge on the south side, and another causeway on the eastern side, indicating careful planning for both defence and access. The final addition was the south-eastern enclosure, which represents the most sophisticated defensive arrangement at the site. This section boasted an impressive trivallate system, meaning three sets of defensive ditches, with the innermost and central ditch carved directly into the bedrock and sections reinforced with granite revetments.

The south-eastern enclosure also contained the foundations of a rectangular structure that archaeologists suggest may have been a gate tower, controlling access to this heavily fortified section of the castle. Together, these three distinct phases of construction tell the story of a site that grew from a simple moated enclosure into a complex multi-period fortification, with the entire defensive system consisting of three earth and stone ditches that would have presented formidable obstacles to any would-be attackers.