Seltannasaggart, also called Corry Mountain, is a low mountain near Lough Allen on the border of County Roscommon and County Leitrim in Ireland; it is the highest point in Roscommon. The mountain is the highest point of County Roscommon. It is part of the Arigna Mountains and rises to a height of 428 metres. On the southern slopes are the remains of a …Seltannasaggart, also called Corry Mountain, is a low mountain near Lough Allen on the border of County Roscommon and County Leitrim in Ireland; it is the highest point in Roscommon. The mountain is the highest point of County Roscommon. It is part of the Arigna Mountains and rises to a height of 428 metres. On the southern slopes are the remains of a promontory fort and sweat houses.