This is a stone bridge over the road near Burrator reservoir. There was an earlier railway line serving Dartmoor but this was itself disused before this branch line was built to get workers to the dam construction site.
It opened in 1883 and closed in 1956. After the dam construction was complete the line remained open mainly serving tourists, as there is no settlement at the dam. Today the area is noted for leisure pursuits, mainly walking and cycling.
They built things to last back then and it is amazing how much attention to detail there was on a bridge support that hardly anyone would ever see. The construction has stood for nearly 140 years already as far as I can tell. What I don't know is if this was built for the original line later reused, because that was built in the 1820's which would make this stone structure 200 years old.
Either way, it looks like it is here to stay and currently still serves as a footbridge on a public footpath.
Burrator Reservoir is a reservoir on the south side of Dartmoor in the English county of Devon. It is one of a number of reservoirs and dams that were built over the course of the 19th and 20th centuries in the area now covered by Dartmoor National Park to supply drinking water to the city of Plymouth and other rapidly growing towns in the surrounding lowlands.