This roughly square enclosure measures approximately 26 metres from east to west and 23 metres from north to south, defined by a series of earthen banks and defensive ditches known as fosses. The site's defensive layout is particularly intricate: three earthen banks with accompanying fosses protect the northern side, whilst the eastern side features a single bank; the southern and western boundaries each consist of two banks with fosses running between them.

The banks themselves remain substantial features in the landscape, with flat tops and steep sides that speak to their original defensive purpose. The eastern bank shows the most wear, standing at about 0.7 metres high on the interior and 0.8 metres on the exterior, whilst the southern sections have become heavily overgrown with vegetation. An external fosse, roughly 0.3 metres deep, can still be traced along the northern, southern, and western perimeters, providing evidence of the site's original defensive circuit.

These moated sites were typically built by Anglo-Norman settlers or wealthy Gaelic families between the 13th and 15th centuries, serving as defended farmsteads rather than true castles. The Tullig example, with its multiple banks and fosses, represents a particularly well-preserved specimen of this type of rural fortification. A field boundary that extends westward from the northwest corner of the inner bank suggests the site's continued influence on the local landscape long after its original inhabitants departed.