The Dorna Bridge, classified as a Property of Public Interest, is located in Dorna, in the parish of Castro Laboreiro. The time of construction is unknown. There are those who refer to the Roman period as medieval or just Roman.
As with many other historic bridges in the Melgaço region, this one was also initially built in Roman times, followed by an intervention of structural consolidation in the low middle ages. Despite the impossibility of establishing a chronological period, it is evident the fact that it presents mixed characteristics, typical of Roman bridges, such as the access by two curves, and of medieval bridges, such as the trestle deck, with a double ramp, the staves of the poorly maintained arch, the irregular filling device and the slab with some gaps. The width of the deck is also related to the medieval period, with about 2.80 m, enough for the passage of animal-drawn cars.