Errew Abbey, Medieval monastery near Crossmolina, Ireland.

Errew Abbey is a former Augustinian monastery on a peninsula stretching into Lough Conn. Its long rectangular church measures 27 by 7 metres and keeps trefoil-headed windows, two sedilia and a piscina. The east side of the cloister is well-preserved but lacks the typical open arcade.

The Barrett family founded an Augustinian monastery in 1413 on top of structures from an earlier foundation created by Saint Tigernan in the sixth century. This layering of two distinct periods shaped the site over the following centuries.

The Irish name Mainistir Taobh Thiar do Shruth means "the abbey on the west side of the stream". The O'Flynn family held the lands as erenachs and came into possession of Mias Tighernain, a paten said to have belonged to Saint Tigernan.

Errew Abbey stands on a peninsula jutting into Lough Conn, with Templenagalliaghdoo immediately to its north. The church measures 27 by 7 metres, so allow time to walk its length and look for the two sedilia and the piscina in the walls. The east side of the cloister is the best-preserved part, though it lacks the usual open arcade.

Templenagalliaghdoo, a small church site immediately north of the abbey, takes its name from the Irish for "church of the black nun." The O'Flynn family served as erenachs of the Errew lands and came to hold Mias Tighernain, a paten said to have belonged to Saint Tigernan himself.