Built of local stone in the late 18th century. The main front, facing E, is of well coursed squared and tooled stone. The central arched opening has graded voussoirs, the opening later reduced to a single door. Irregular slate hipped roof, recently renewed, over a coved eaves course without gutters, rising to a central louvred glover, with its own slated hipped roof. The interior is lined with nest boxes constructed with brick, each tier separated by a slate flight ledge. The boxes are 20 high on three walls and 12 high on the entrance wall, totalling 864 nest boxes. The roof structure has been reconstructed in recent times, without a central potence.
Associated with Ynysmaengwyn House (Nprn 54223)
Source: ME/DOM/SH50SE, from the Cadw Listed Buildings Database
J. Archer, RCAHMW, 31.12.2004