The "bridges" were formed by the erosive activity of the once larger Erkyupryia River.
It transformed the marble clefts into a deep-water cave, the ceiling of which eroded through time and collapsed, possibly during an earthquake.
The larger Wonderful Bridge is passable under the vaults, where birds nest in the marble clefts.
A third, small and inaccessible, formation follows, the entrance to a pothole where the river's waters disappear underground, reaching a sump after 3 km.
The site can be reached by an asphalt road and is about 30 km from the closest town, Chepelare.