Mongavlin Castle

Mongavlin Castle is a stone fortress on the western bank of the River Foyle in County Donegal. The ruins span three levels and display the compact construction typical of medieval defensive structures in this region.

The castle was built in the 16th century as a residence for Finola MacDonnell, wife of Hugh O'Donnell, who arrived with Scottish guards from the Crawford clan. The site later figured in military campaigns during the 17th century in northern Ireland.

The name derives from the Irish Maghgaibhlin and refers to a small fork shape in the surrounding plain. Visitors can still observe this geographical feature in the landscape today.

The ruins are located about 5 kilometers south of Saint Johnston village and accessible via country roads. The site sits in a rural area, so visitors should expect limited infrastructure and bring weather-appropriate clothing.

King James II wrote a letter from this location in 1690 proposing the surrender of Derry. This correspondence marks a significant moment in political history during his campaigns in northern Ireland.

Location: County Donegal

GPS coordinates: 54.90417,-7.45333

Latest update: December 8, 2025 21:03