This particular example at Straid stretches approximately 50 yards through the earth, its stone flagged walls creating a corridor roughly four feet wide. The passage maintains enough height for a person to stand upright through most of its length, though several lower arched sections require visitors to crawl through on hands and knees.

The construction shows the careful engineering typical of these enigmatic structures; stone flags form both the walls and ceiling, whilst the floor consists of packed clay that has remained remarkably clean over the centuries. Along the main passage, several small chambers branch off, creating additional spaces whose original purpose remains a matter of scholarly debate. Were they storage areas for food and valuables, temporary refuges during raids, or perhaps ritual spaces with spiritual significance? The souterrain at Straid keeps its secrets well.

First documented by M. R. Colhoun and later included in the comprehensive Archaeological Survey of County Donegal in 1983, this souterrain represents just one of many such structures scattered across Ireland. These underground passages, dating from the early medieval period, offer a tangible connection to the lives of those who once farmed these same fields, their hidden architecture a testament to both practical necessity and remarkable construction skills that have endured for over a thousand years.