Known as Pont Fawr in Llanwrst, on the River Conway, the original bridge at a previous ford crossing was declared unsafe in 1626. In 1634, Lancashire stonemasons were contracted to build a replacement but the workmen inserted the arch keystones upside down culminating in the collapse of the bridge on its opening day. Today, the narrowness of the bridge can only accommodate a single lane crossing and the hump does not provide forward visibility. It has a local nickname of “Bridge of Swearing”. The River Conway is a conduit for rain and meltwater from a large area of Snowdonia and the bridge structure has proved to be very resilient in times of flood.