The remains of the former parish church of Killean, dedicated to St John, was first on record about 1222. The church continued in use until abandoned in 1770. The greater part of the building is roofless, but apart from the West gable-wall, which has been entirely removed, the walls are in a fairly good state of preservation, although partially covered with a dense growth of ivy.
Killean has a number of sculptured stones belonging to the Iona School and of 14th-15th century date.
One is a beautifully carved example of a fully-armed knight: he has a pointed bascinet (helmet), protective mail covers his shoulder and neck and he wears a long sword with belt fastenings and a ribbed tunic.