Known as Caherlea, or An Chathair Léith in Irish, it is a cashel, the stone-built equivalent of an earthen ringfort, constructed from a rubble core faced on both sides with drystone masonry. The wall runs to about 2.1 metres wide and up to 1.5 metres high, enclosing a roughly circular interior some 23.6 metres across. Along the eastern side, part of the wall has been reduced to a low mound, its outer face patched with modern stonework that appears to follow the original line. Where exactly the original entrance once stood is uncertain; it may have been at the northwest, where a field wall joins the cashel wall, or somewhere in the poorly preserved northeast sector.

What makes Caherlea particularly worth attention is what lies beneath it. A souterrain, an underground passage and chamber system built from drystone masonry and used in early medieval Ireland likely for storage or refuge, runs roughly northeast to southwest beneath the cashel wall at the southeast. The accessible portion comprises two small chambers connected by a short passage. The northeastern chamber is oval in plan, measuring roughly 2.8 by 2.25 metres, though its roof has collapsed and the debris now obscures much of the interior. A blocked passage leads northwest from this chamber, only 37 centimetres high at the point where collapse has sealed it, and a surface depression a little further along may mark another section of the underground system, possibly its original entrance. The southwestern chamber is better preserved; its roof slabs step upward as the passage widens, reaching a height of about 1.45 metres inside the chamber itself. The walls of the chambers are corbelled, meaning the stones are laid in overlapping courses to form a rough vault, a technique requiring considerable skill and still clearly legible in the surviving sections. In the southwest of the interior above ground, low foundations hint at the former presence of one or possibly two huts, though their shapes are no longer recoverable. The site was documented in detail by J. Cuppage in the 1986 Dingle Peninsula archaeological survey.