This ancient earthwork occupied a stretch of good pasture land in a valley that runs north to south, taking advantage of the fertile ground near the river. Today, however, visitors to the site will find no visible trace of this prehistoric monument; it has completely vanished from the landscape, known only through historical records and maps.

The enclosure was documented on the 2nd edition of the Ordnance Survey 6-inch map, which served as one of the primary records of its existence before it disappeared. These circular or near-circular earthworks, typically consisting of a bank and ditch, were common throughout Ireland and often served as defended farmsteads or ceremonial sites during the Iron Age and Early Medieval periods. The location near the River Aighe would have provided the enclosure’s inhabitants with a reliable water source and productive agricultural land.

This lost monument was catalogued as part of the comprehensive Archaeological Survey of County Donegal, compiled in 1983 by Brian Lacey and his team of archaeologists. The survey documented field antiquities spanning from the Mesolithic Period through to the 17th century, preserving crucial information about sites like An Caiseal that have since been lost to time, agricultural improvement, or natural erosion. While the physical structure may be gone, its inclusion in this archaeological record ensures that the memory of this ancient enclosure remains part of Donegal’s rich historical tapestry.