On the southern shore of Lough Melvin in County Leitrim, a curious rectangular earthwork once stood on the lower slopes of a northeast-facing hillside.

At the eastern end of an old silted loop of the Bonet River in County Leitrim stands the remnant of Harrison's Castle, a fragment of Ireland's turbulent plantation history.

Parke's Castle in County Leitrim stands as a remarkable example of a 17th-century fortified manor house, its distinctive five-sided bawn walls rising 4.5 metres high on most sides.

At the end of Corry Point, a wooded peninsula jutting into the northern shore of Lough Allen, stand the remains of what was once Fordes Castle.

On the north shore of Lough Gill in County Leitrim stands Parke's Castle, a fascinating example of how one man's 17th-century renovation project transformed a medieval Irish tower house into something quite different.

On the northern shore of Lough Gill stands the remarkable remains of what was once the principal residence of the O'Rourke clan, one of medieval Ireland's most powerful Gaelic families.

At Parke's Castle in Kilmore, County Leitrim, visitors can explore a fascinating tale of architectural transformation that spans centuries.

Tucked away in woodland just 25 metres from the eastern shore of Lough Rinn stands a medieval castle with a bloody past.

Hidden among the rolling countryside of County Leitrim, the remnants of Drumany Castle offer a glimpse into Ireland's complex medieval past.

Perched on a rocky outcrop in the Glencar valley, the ruins of Castle Car tell a violent tale of Ireland's military evolution.

Perched on a gentle hill overlooking the Owenbeg River, the ruins of Manorhamilton Castle tell a tale of ambition, conflict, and ultimate abandonment.

Tucked away on Crane Island, a small wooded isle measuring roughly 125 metres north to south and 70 metres east to west, lie the overgrown remains of a 17th-century fortification.

Perched on a gentle slope overlooking Lough Bofin, the site of Aughry Castle tells a tale of Scottish settlers and Irish conflict.

On a gentle rise in the rolling countryside near the Ballinamore and Ballyconnell canal, the site of Castlefore holds centuries of Irish history beneath its now empty fields.

Castle John stands on a rocky promontory jutting into Lough Scur in County Leitrim, a spot that was once completely surrounded by water and known as Castle Island.