Errigal Church and Souterrain is a reminder of the coming of Christianity to this region. It is said that this Church was founded by St.Adhamhnan in the 7th Century. The Souterrain may have been used either as a place for storage or a place in which to hide when the monastery was under attack. It contains a number of chambers. A large stone with a hole carved in it can be found close to the Church. This is known as Bullaun Stone. Such stones are often found at early Christian sites and the water which gathered in the hole was often used for cures.

Just off the Gortnamorragh Road lies an important monument used by local Gaelic rulers until the late 16th century. There is a large rock containing what appears to be the tracks of two footsteps. There is a local legend that these footprints were left in the rock in the 7th Century by St. Adhamhnan but it is more likely that the monument is the inauguration site of the Chief of the O’Kane (O’Cathain) Clan. The incoming Chief will have stood in these footprints forming a link between earth and heaven as he took his oath of supremecy.

The area contains many other antiquities such as Farrantemple Fort, Uagh Ullin Cairn, The Drumbane Hut sites, Tamnyrankin Court Cairn and the Curragh Hut Site to name but a few. These ancient sites, along with the more modern monuments such as the Mass Rock and Glen Old Chapel, Lagnamuck are a guide to the way in which people in Glenullin lived, worshipped and died. Many of the sites can be investigated on the Waymarked Trails that have been developed by the Glenullin & Agivey Conservation and Development Group.