Remains of a fortress between the villages of Kolarovo, Izvorovo and Yersusalimovo. It is located at the foot of the Bakarlya area, northeast of Dositeevo village. The fortress can be reached by car on a paved road up to about 2 km before the site. The remaining 2 km must be covered on foot.
Castra Rubra flourished during Roman times. It was built along the ancient Roman road Via Diagonalis. This road was the reason for the development of a roadside facility at the site, where the Roman state postal service could change horses. Auxiliary buildings were gradually constructed to guard the Roman road and the merchants travelling along it. Further remains from antiquity can be found in the land belonging to the village and around the ancient road, including various structures, mines, necropolises and others.