Vishegrad (Bulgarian: Вишеград) is a medieval fortress in the Rhodope Mountains of southern Bulgaria rising over a promontory in the valley of the river Arda.

[1] Vishegrad is located on a 306 m height rising on the right bank of the river Arda over the modern Studen Kladenets Reservoir.

Both Vishegrad and Monyak and were likely constructed to the protect the region around the mouth of the river Varbitsa, which was part of the secondary road between the major cities of Philippopolis and Adrianople.

The two fortresses and the village are located on a curved slightly elevated line connected by natural saddles with a gentle slope to the river.

The walls are approximately 2 m thick and preserved to a height of 1 m.[4] The masonry is made of rough stones, joined with mud mortar, and in some places the joints are filled with small pebbles and earth.

[2][7] Along with the nearby fortifications of the Monastery of John the Precursor and the adjacent medieval settlement that existed in the 9th–14th century, Vishegrad is considered to be the progenitor of the modern town of Kardzhali.

In the western half of the northern wall, an external stone staircase has been preserved, which served as an access the second floor of the tower, as the first one was used as a reservoir.