The Tegernacus stone is a large, irregular upright slab, measuring about 2.25 metres high, 1.0 metres at its widest and 17cm to 22cm thick. The rough surface of the stone bears a four line Latin inscription vertically down the face - TEGERNA/CUS FILI/US MARTI / HIC IACIT. It was originally placed near a trackway on the Cefn y Brithdir ridge, above New Tredegar, and would have been visible to those using the trackway. The seventh century inscribed stone was moved to the National Museum of Wales in 1923.
The stone was originally located about 150m to the north-east of Capel-y-Brithdir. A concrete slab now marks its original position.
Additional source:
Early Christian Monuments of Wales by Nash Williams.

RCAHMW, 17 November 2015