Wonderful bridges or also known as the Rock Bridges are a rock phenomenon located in the karst valley of Erkupria River in the Western Rhodopes at 1450 m above sea level at the foot of the Goliam Persenk Peak.
Bridges have been formed as a result of the erosive activity of a deepwater river in the past, which has transformed cracks in the marbles into a deep water cave whose ceiling over time has thinned and collapsed. As a result, the two famous marble bridges remained.
The big one is about 15 meters wide in the broader parts and almost 100 meters long. It consists of three arches, the largest being 45m high and 40m wide.
The small bridge is 200m away from the big one. It has a length of 60 meters, a height of 50 meters, with only the height of the arch 30 meters. Next to it there is a very small third bridge, which is a subterranean cave in which the Erkupriya waters disappear to return to the surface after 3 km.
The area around the two bridges is occupied by centuries-old coniferous forests, consisting mainly of spruce trees. Both bridges are secured by railings.
