Rail bridge over Agueda River, near its river mouth, into Duero River. No trains anymore; nowadays, it's used as a trekking route known as Camino de Hierro (Iron Trail).
The bridge connects Spain (the side with a tunnel), also with Vega de Terrón pier, with Portugal. You can also see another bridge with the equivalent road.
I didn't have a tripod and took the photographs with the camera handheld. Consequently, there are some parallax errors in the stitching, particularly in objects near the photographer, due to the camera not rotating on its nodal point.