[3][4] The ruins sit on a hillside in the south-west of County Fermanagh, between Blacklion and Cladagh Bridge, very close to the Hanging Rock and overlooking both the Gortatole Outdoor Education Centre and Lower Lough Macnean.

The original name of the village was Largay (also Largy, Largain, Largin and Largan, from the Gaelic Leargaidh meaning a hillside), which was part of a túath belonging to the Coffey McGoverns, a sub-sept of the Mac Shamhráin (McGovern or Magauran) clan, from the 9th century until the Plantation of Ulster in the 17th century.

O'Donnell then set out with a small number of his forces to hire them; and he left another large party of them with Maguire to assist him, and he ordered them to remain blockading the castle.

When the Lord Justice, Sir William Fitzwilliam, had received intelligence that the warders of Enniskillen were in want of stores and provisions, he ordered a great number of the men of Meath [Kingdom of Mide], and of the gentlemen of the Reillys and the Binghams of Connaught, under the conduct of George Oge Bingham, to convey provisions to Enniskillen.

The route taken by George Oge Bingham and the few who escaped with him from the field was through the Largan, the territory of the Clann-Coffey Magauran, through Breifny O'Rourke, and from thence to Sligo.

To hold for ever, as of the Castle of Dublin, in common socage.In the Commonwealth Survey of 1652, the lands were owned by Thomas Worship (alias Worsopp) and the tenant was Lan Lawther.

On 21 August 1625, the Fermanagh Assize Judges wrote from Enniskillen to The 1st Viscount Falkland, Lord Deputy of Ireland, as follows-[8] On 20 August 1625 Phelim bane McCabe swore: The name was changed to Blacklion in honour of a famous coaching inn in the village.

About a quarter of a mile to the R. of Largay, or the Black Lion inn, is Belcoo Bridge, which leads to Garison [Garrison] road.

So we made a hearty supper, called in as many as pleased of the family to prayers, and, though we had no fastening either for our door or our windows, slept in peace.

[11] Blacklion's urban growth was hampered until the mid nineteenth century by the nearby village of Red Lion, some miles to the west on the coach-road to Sligo.

The weather event known as The Night of the Big Wind in January 1839 caused structural damage to the Protestant church at Thornhill, to the west of Blacklion.

Learga is the plural of an Irish word Learg meaning rising ground, slopes, or mountain side.

Attractions near Blacklion include the lakes of Upper and Lower Lough MacNean, the Marble Arch Caves, the Cladagh Glen Nature Reserve, Florence Court house and grounds, Glenfarne forest with its lakeside walks, Shannon Pot (the source of the River Shannon, Ireland's longest river) and Cuilcagh Mountain Park.

3 kilometres (2 mi) south of Blacklion lies the Cavan Burren, a limestone landscape containing a number of Neolithic remains, which was planted with forestry in the 1950s and has since been partially reclaimed and signposted to provide access to its structures and geological features.

Upper Lough Macnean is known as a coarse fishing lake and contains bream, roach, hybrids, pike, perch, eel and brown trout.

Blacklion is home to the most westerly and northerly Gaelic Athletic Association club in County Cavan, the Shannon Gaels.