A cashel is simply a ringfort built from stone rather than earthen banks, a circular or near-circular enclosure that would once have sheltered a farming household, their animals, and whatever modest wealth they had managed to accumulate. Thousands of these structures survive across Ireland, yet each one occupies its particular patch of ground with a specificity that resists generalisation.

Ringforts of this kind were in use primarily during the early medieval period, roughly between the fifth and twelfth centuries, though some enclosures have earlier origins and many continued to be occupied or reused long after that. In the west of Ireland, where good building stone is rarely far from the surface, cashels are especially common, their dry-stone construction often proving more durable than the raised earthen rims of ringforts in other parts of the country. Doonowen lies in south Connemara, a part of Galway where the interaction between farmland, bog, and coastal inlet has shaped settlement patterns for millennia, and where field monuments can sometimes be read almost as a continuous record of that long occupation.