The monument comprises the remains of Teampull na Trionaid (Church of the Holy Trinity), the building known as Teampull Clann a' Phiocair (Chapel of the MacVicars), associated structures and graveyard at Carinish, North Uist. The monument was first scheduled in 1969 but an inadequate area was scheduled: the present scheduling rectifies this.
Teampull na Trionaid survives as a ruin measuring from 6.5m by 18.75m with walls 1.1m thick standing up to 6m high in places. Evidence for its construction, including putlog holes, survives. The building is difficult to date on architectural grounds because the only surviving feature is a much-eroded lancet window near the E end of the N wall which could date between the 13th and early 16th centuries. From documentary sources it is known that a church existed here in the early 14th century, and there is a tradition of it being founded by Bethag, daughter of Somerled in the late 12th century. Other oral traditions hold it to have been an important place of learning in later medieval times at which the Franciscan philosopher, Duns Scotus (c. 1265-1309), among others, received part of his education. Ownership of the site was transferred several times, including to Inchaffray in Perthshire and Iona in Argyll.
The church features in accounts of the battle of Carinish between the Macdonalds and a raiding party of MacLeods from Harris in 1601, when it was used as a sanctuary. Various modern place-names (Cnoc na Croise Mor and Noncan na Croise Beage for surrounding knolls) suggest that this sanctuary may have been marked by stone crosses. The precise extent of such a sanctuary and other structures that might have been expected within it, is not known.
Tradition holds that the school continued to function until the 18th century; at the beginning of the 19th century the inside of the church was still decorated with sculpture and the E gable supported a spire, or niche, decorated with three heads.
To the N side of the church is the building known as Teampull Clann a'Phiocair, a name probably dating from post-Reformation. times when the building was used as a family burial place. The rectangular building is later than the church and attached to it by a barrel-vaulted passage. The domestic character of this building suggests it may have functioned as a priest's house rather than a sacristry. Its steeply-pitched gables once supported a timber roof. The E wall contains a splayed lintelled window flanked by wall cupboards; on the W is a single window and cupboard.
The majority of the gravemarkers visible in the graveyard are relatively modern, but it can be assumed that the graveyard includes burials dating from later medieval times onwards. The sub-circular form of the graveyard may hint at earlier origins, perhaps suggesting there might have been an early medieval church here too. Modern burials and memorials can also be found in the inside the ruined buildings.
The area to be scheduled is irregular on plan, extending approximately 5m in all directions beyond the outer walls of the churches and graveyards, to include the churches, graveyard and an area beyond in which associated remains may survive, as marked in red on the accompanying map extract. Active burial lairs, visible gravemarkers, above-ground elements of modern field boundaries abutting the site and existing field drains are excluded from the scheduling, to allow for their maintenance.