The rath at Altanelvick sits on a natural rise with a steep drop to its western side, and its builders made full use of that topography. A ringfort, or rath, was typically a circular enclosed farmstead of the early medieval period, home to a family of some local standing, defined by earthen banks and ditches that signalled both security and status.

The earthwork here is substantial by any measure. The central platform, roughly 34 metres across, sits atop a mound of earth and stone that rises nearly three metres at its highest point, and is enclosed by a bank almost ten metres wide in places. Around the base of that mound runs a fosse, a defensive ditch roughly two metres wide, with its own outer bank beyond. The northern and eastern sections of the fosse and outer bank survive well; elsewhere they have been absorbed into later field boundaries, with a north-to-south wall running along the western side and another built directly on top of the original bank from west through north to north-east. A three-metre gap in the eastern bank is the probable site of the original entrance, and the ground outside it shows signs of disturbance, with field clearance stones scattered toward a corresponding break in the outer bank. Perhaps the most unusual feature is a raised U-shaped area projecting from the northern bank, measuring roughly 34 metres north to south and 25.5 metres east to west, its eastern edge kerbed with stone and its inner face defined by a low scarp. What purpose this annexe served is not recorded. A hollow in the eastern quadrant may be a quarry hole, suggesting that material was extracted on site during construction or later modification.