The Fortress is located 3 km from the town. The castle was built on a rocky peak inaccessibility to Asenitza River . The earliest finds from archaeological excavations date back to 5-4 c . The area has been inhabited by the Romans, Byzantines and Bulgarians.
At the time of the Thracians the fort played an important role in defending the passage, connecting the territories of ancient Thrace to the Aegean . Byzantine Emperor Justinian did rise in that placein order to stop enemy incursions from the north. After numerous raids and battles , the fortress is still standing upright. Early Middle Eastern Rhodopes are within the first Bulgarian state and city walls protect its territories from foreign invaders . In the region was a medieval town Stenimachos . In the 13th century , having expanded the territory of Bulgaria to three seas – White, Black and Adriatic Bulgarian Tsar Ivan Asen II strengthened the fortress. Large-scale construction is charted in Bulgarian at its entrance. Message carved on the rock causes the fortress and the nearby modern town to be called Assen’s town.
The Outer wall has been well preserved. It has a height of 3 meters and a thickness of 2 m and it is clearly visible as it is situated at the highest point with an inner citadel tower. In peacetime, it served as the residence of the governor , and during the war was used as a watchtower and a safe haven from the enemy.It Can trace the outlines of reservoirs whose walls were lined with ceramic pieces .
The biggest attraction of the fortress is the medieval Christian church ” Mary of Petrich . ” Nave domed church was built in the 13th century by the order of Tsar Ivan Asen II. The tower of the temple served both tower and watchtower . The church itself has two floors , the first floor , according to the original intent of the builders was scheduled for crypt . The actual church is on the second floor . It is built with specially quarried and cut freestone blocks. The facade is indented to blind arches. Interestingly natural stone iconostasis characteristic of medieval Bulgarian church prior art and popular during the Renaissance wooden iconostasis . Part of the interior decoration of the church , however, was destroyed . During the earthquake in 1928, its dome collapsed , leaving precious frescoes of the arbitrariness of the raw mountain climate. It was later restored , thanks to it today we have some great fragments of frescoes dating back to the 14th century. This is actually the second mural layer.The firts Was applied in the 13th century , during the construction of the temple.
Since the beginning of the 90s of the 20th century the church functions as a church . It helds services associated most often with baptisms and weddings . The rest of the fortress and the church is open to visitors. The disposal guide introduces people to tumultuous past that is steeped in history span land. Assen’s fortress is visited by about 70 thousand tourists per year.