What makes Cathair an Lóthair, or Loher Fort, worth attention is not simply that it survives, but how much of its interior life has been preserved and, through excavation, revealed. Inside the roughly circular caher wall, a cashel being a type of stone ringfort enclosed by a dry-laid stone boundary rather than an earthen bank, stand the remains of two separate drystone houses. The fact that both are still legible, with walls standing to over a metre in places and a paved pathway connecting the rectangular house to the entrance passage, gives the site an unusual degree of spatial coherence.

Excavations carried out by O'Flaherty in the early 1980s showed that the site accumulated in layers over time. The circular house, 6.6 metres in internal diameter and set into the northeast quadrant of the enclosure, was not the first structure on that spot; beneath it lay an earlier stone-built circular structure, and beneath that again the traces of a wooden building made from driven stakes. The rectangular house, measuring roughly 7.55 by 6.3 metres and occupying most of the western half of the interior, was similarly preceded by a stake-built circular structure. A souterrain, an underground passage built for storage or refuge, was cut into the floor of the circular house some time after the house itself was built; it runs east to west for three metres before turning sharply north. The caher wall itself is up to four metres thick at the base and features a terrace on its inner face, accessed by seven separate arrangements of opposing steps set into the wall at irregular intervals. A second partial terrace survives above the first in the northern sector. The entrance to the whole enclosure is a lintel-covered passage, four metres long, running in from the south-southeast, wide enough to pass through but low enough to require some attention.