Ty-ffynnon Bridge over the Monmouthshire and Brecon Canal & attached revetments and Lock

Ty-ffynnon Bridge is a bridge with an attached lock located over the Monmouthshire and Brecon Canal. The towpath runs along the west side of the canal. The bridge is constructed from rubble and features a segmental arch made of stone voussoirs. It has flat parapets with cement copings. The splayed revetments extend south for about 20 metres, rising towards the eastern side where the mouth of an overflow culvert is located, which runs to the east. The culvert mouth is roughly arched and also made with stone voussoirs. Almost directly opposite, there is a small segmentally arched opening that allows a drain to pass under the towpath and into a stone-lined culvert. The lock chamber is built of stone and brick, with ashlar quoins and sandstone copings. There is a later weir at the northern end, and rebates for gates are present at each end of the lock.