The ruined church known as St Feichin's church (Tempull Mór Feichin) is a single-cell structure incorporating some Romanesque features. It has an E window (obscured by ivy) and two tall, narrow, round-headed S windows of one recessed order, splayed on the interior. The church was once divided into an upper and lower level at the W end and has a small, low, square window in the N wall and a blocked doorway with inclined jambs in the upper W wall. There is also a rectangular window high up in the W end of the S wall, with a row of holes for joists below. A roll is carved on all the exterior angles of the building apart from the NE angle. There are other building remains on the site but these are very overgrown. Sculpture is found on the very weathered rebuilt S doorway.

Gwynn and Hadcock (1970, 160) record that an early monastery was founded at Ballysadare by St Feichin of Fore in the 7thc. and that an Augustinian Abbey existed there in the 12thc., possibly prior to 1166. The Augustinian Canons moved to a new site a short distance to the W of the original site (Killanin and Duignan). Archdall records that the abbey was burned in 1179 and again in 1188 (?source) and the Annals of Connaught record that the area from Ballysadare southward was ruined in 1228. Gwynn and Hadcock suggest that this may have led to the Abbey Church being rebuilt.

Leask compares the heads on the doorway with those at Inchagoill in Galway. The building is now almost completely obscured by ivy (2003).