This one asks something harder: to consider what is entirely gone. In undulating pasture near Glebe in County Mayo, there is no visible surface trace of a cashel that once stood here, its walls two metres high and three metres thick, enclosing roughly half an acre of ground. A cashel is a stone-walled ringfort, the enclosure type most common in the west of Ireland, typically used as a defended farmstead in the early medieval period. This one also contained a small circular building within its interior. Today, the ground gives nothing away.

The cashel was known as Caher-Mac-Turc, and it survived long enough to be remembered, if not recorded in stone. Around 1820, it was demolished, and the material did not simply disappear. William Wilde, writing in 1872, noted what had happened: the stone was taken and used in the construction of Glebe House nearby. This was not an unusual fate for old structures in the nineteenth century, when substantial dressed or field stone was a practical resource rather than a protected heritage. The name Caher-Mac-Turc, meaning something close to the fort of the son of the boar, suggests a site with its own local identity and perhaps its own story, though that story has largely dissolved along with the walls themselves.