The Krivus Fortress played a major defensive part in the Arda region. It was built around the 10th century on a picturesque rock above the Arda River, at the place where the river forms its famous meanders. There is not much left of the fortress today: only a few walls with a height up to 5 meters, an entrance and some loop-holes. Krivus owed its impregnability to the fearful abysses on three sides of the fortress. It is fully surrounded by lovely tall ridges, dotted with a big number of small villages with colourful architecture. The Bezdiven Peak is distinctive. Apart from the unforgetable scenic views that open in front of the eyes at the top, the feet of the peak keep the remains of the medieval fortress called Patmos, built on a pinnacle by the waters of the Kardzali Dam.
The Krivus fortress is repeatedly mentioned in the chronicles of Byzantine historians, and archaeologists discovered decorations, coins and weapons in it. The only way to the fortress passes through the village of Bashevo, which has preserved its archaic appearance, and the people living there are almost untouched by modern civilization.