At Mullenmadoge in County Mayo, there may once have been a souterrain concealed within a rath, yet today there is nothing visible at ground level to confirm it. A souterrain is an underground passage or chamber, typically built from large flat stones and associated with early medieval settlement, often used for storage or as a place of refuge. A rath, meanwhile, is a roughly circular earthen enclosure, the remains of a farmstead that might date back well over a thousand years. Together, they would have made for a quietly formidable little complex. As things stand, neither can be confirmed with any certainty.

What is known comes largely from local memory. At some point in the past, large stones were uncovered and removed from the enclosing bank of the rath. Those stones may have been structural elements of a souterrain, the kind of substantial slabs used to line and roof such underground features. A personal communication from M. Ruane in 1991 brought the possibility of the souterrain to wider attention, but no excavation appears to have been carried out to settle the question. The rath itself is described as a possible example of the type, so even the enclosure that might have housed the underground structure remains unconfirmed. What was once potentially there has been dismantled, removed, and forgotten, leaving only the suggestion of something that once mattered enough to build.