A Roman fort near Cwmdu (Pen-y-Gaer) is also of significance to Talgarth as there was a Roman route from Abergavenny via Pen-y-Gaer up the Rhiangoll valley to Talgarth, some experts say to Castell Collen near Llandrindod. Much evidence has been lost in the intervening 2000 years, but there is growing circumstantial evidence to suggest there is a missing Roman fort in the Talgarth area, at the crossroads of two or possibly three Roman routes, the Roman road from Pen-y-gaer, from Clyro to Y Gaer near Brecon and even the river Llynfi itself, although the latter may not be acceptable to some archaeologists. Nevertheless, water routes, even small ones are not unknown to have been used for man-hauling equipment in small, narrow flat bottom boats.