St. Mary’s Church, Castlerahan was built in 1834 at a cost of £2,000 by Fr. John O’Reilly, Castlerahan, who died in 1842, and whose tombstone (and tomb) is in the church. It is a large structure, built of stone and has seating for about 500 people. It was renovated in 1975 by Fr. Tommy Murray CC, and this has considerably brightened up the interior.