After the Anglo-Norman colonization of Louth in the late 12th century, Termonfeckin evolved into a medieval borough.[*1] While little is known of its layout and size, it was sufficiently important to have possessed a parish church (on the site of the present Church of Ireland) and two castles. Both of these appear to have been Tower Houses (see Roodstown Castle for general details on this type of castle). Only one of these Tower Houses survives today, but when Thomas Wright visited Termonfeckin in the 1740s both of them were standing. Possibly because of its associations with the famous Archbishop Ussher, Wright chose to record only one of these castles (Louthiana, Book II, Plate XIX-XX).

Ironically, this tower has now vanished, though its site is well known: it stood just south ofon the river bank at the western end of the village just south of the bridge. It certainly still stood in 1791 (see illustration) but was gone by the time the Ordnance Survey of Ireland visited Termonfeckin in the late 1830s.

The surviving tower house (see isometric view) stands at the eastern edge of the village. It is a three storey rectangular building which originally had projecting towers on its N and S angles. However, it has been the subject of major alterations at some time in its history, particularly on the ground storey. These alterations are possibly the work of one Captain Brabazon who is documented as having 'repaired' the castles in Termonfeckin in 1641 (Harbison 1970, 166). The castle's major architectural feature is the very fine stone-built vault which spans the 2nd storey. This employs the same building technique - corbelling - as the roof of the prehistoric passage tomb at Newgrange, which lies only 15km to the south-west. While it is tempting to speculate about 'connections' between these two monuments, it is best to put down the occurrence of corbelling to co-incidence rather than 'continuity'.

Ruined

https://www.wikiwand.com/en/Termonfeckin