It is thought to have been built by a Norse chieftain, Kolbeinn hrúga or his son, Bjarni Kolbeinsson, Bishop of Orkney.
The now roofless Romanesque style building was originally constructed of local rubble and lime mortar.
Historic Environment Scotland established the site, which includes the church and walled burial ground, as a scheduled monument in 1929.
The church and surrounding cemetery lie at the bottom of the hill where the ruined medieval fort, Cobbie Row's Castle stands.
During the restoration, a grave was uncovered inside the chapel with the remains of a tall, powerfully built man.