This medieval round tower stands approximately 15 metres high and has an external diameter of 14 metres. It is built almost entirely of quarried red sandstone rubble, derived from the east end of Peel Bay.  The tower lies on the same east-west axis as the nearby St Patrick's church and is interpreted as having a common origin and related religious purpose. It is more or less consistent with Irish towers built at Christian communities from the 9th and 10th centuries onwards and, together with examples at Brechin and Abernethy in Scotland, is one of only three known to exist outside Ireland. 


The uppermost masonry present, forming a battlemented parapet and built on a course of corbels, is of a different style of construction. It is therefore thought to be of later date. The parapet is shown on a mid-17th century drawing, which also apparently depicts a conical roof, of the kind typically seen on Irish examples, at the top of which now stands a flagstaff.


The tower is entered through a doorway elevated circa 2 metres above ground level, and faces east towards the church. Until the early 20th century masonry steps provided access, but these were not tied into the masonry of the tower and appear likely to have been a later addition.


The interior of the tower has been excavated on three occasions, although no information survives recording work undertaken in 1876-1889 and 1906.  In 1929 a flagged floor was lifted and the interior excavated down to the bedrock on which the tower is founded, which is also visible outside. The material was described as 'rubbish, old mortar and stones' and was interpreted as backfill from the previous excavations.