Killagha Abbey, also known as Kilcolman Abbey, was erected on the side of an older monastery around the 12th century. It was a very wealthy Abbey and held a lot of local power and had connections with the Irish House of Lords. Unfortunately, it was a victim to Cromwell's soldiers and never able to regain its former glory. This was once a very impressive building and traces of its architecture can still be seen to this day. Only the church with a single long nave remains, as well as the associated graveyard, but one can visit and view the well known East Window which was restored by a local community group.

It is situated outside Milltown Village, on the banks of the River Maine, just off the N70 road.