Named after Zeynel Bey, this mausoleum is on the less-built opposite (northern) banks of the river (and as such easily distinguishable from the surroundings), with its outside covered with charming blue mosaics of geometrical designs and calligraphy, although somewhat worn out. Bey was the son of Uzun Hassan, the ruler of the Akkoyunlu Dynasty which ruled over Hasankeyf in the 15th century.