The mountain's name refers to an ancient burial cairn on its summit, and to Lord Clermont of Ravensdale.

[4] It was built in the early Neolithic, c. 4000–3500 BC, and forms part of the Clyde-Carlingford group of court cairns.

[7][8] The Clermont Carn transmission site is situated at the summit of Clermont Carn and was opened in 1981 to provide UHF television coverage for the northeast of the Republic of Ireland, counties Louth, Meath, and North County Dublin.

With the site being less than two kilometres (1.2 mi) from the border it was clear that this transmitter would be used to provide RTÉ services into Northern Ireland.

Today the Irish digital television service Saorview is broadcast from here to a sizeable area including a large tract of Northern Ireland, with a good signal being received in Belfast and beyond.