The history of the Harmanfortress is linked to the presence of the Teutonic Knights in Barsa in the first decades of the thirteenth century, in Feldioara, Prejmer, Rasnov, and Sanpetru. The first document that names the settlement dates from March 21, 1240, 15 years after the expulsion of the Teutonic Knights from this territory.
Probably in 1240, when the Cistercians took over the Roman basilica , the three naves have been under construction. The majority of the actual shape of the construction dates from that stage.
The fortification surrounding the church was built in the fifteenth century. It consists of a triple cord curtains concentric fortifications similar to the one in Sanpetru. The exterior wall, is not so high, having a height of just 4.5 meters being designed to protect the enclosure.At the same time it was establishing the limit of the moat that surrounded the fortification. The third belt that surrounded the ditch moat at the exterior no longer exists. The inner wall, 12 meters high had seven towers for the deffence of the fortification.