A single cell church, very overgrown. The E wall is missing. There is a round-headed doorway in the N wall. A 13thc. window in the E end of the S wall has a continuous roll but is otherwise plain. The interior is filled with graves, and a barrel-vaulted mausoleum has been built beneath the S window.

The Tripartite Life of St Patrick records that the Church was founded by St Patrick for Bishop Maneus (Maine) and Gentene, and Gwynn and Hadcock list Aghanagh in an appendix of early sites. Petrie, quoting the Tripartite Life of St Patrick notes that the foundation is also recorded in the 'annotations of Tirechan' in the Book of Armagh.

Petrie records, incorrectly, that there is a continuous roll on each order of the doorway. He gives the dimensions as follows: outer h. 2.36 m x w. 1.47 m, inner h. 2.13 m x w. 1.02 m. Petrie has an illustration of the doorway (1845, 180). NW of the site is Maine's Well (Tobar Mhaine).