Hyrcania (Ancient Greek: Ὑρκανία; Arabic: خربة المرد "Khirbet el-Mird"; Hebrew: הורקניה Horcania) was an ancient fortress in the Judean Desert. It was built by Hasmonean ruler John Hyrcanus or his son Alexander Jannaeus in the 2nd or 1st century BCE (in the Hellenistic part of the Second Temple period). The site is located on an isolated hill about 200 m above the Hyrcania valley, on its western edge. It is in Bethlehem Governorate in Palestine, about 5 kilometres (3.1 mi) west of Qumran, and 16 kilometres (9.9 mi) east of Jerusalem.
Initially destroyed by Gabinius, the fortress was rebuilt and greatly expanded by King Herod (r. 37–4 BCE; Roman period). After Herod executed his son Antipater, he was interred there. After Herod's death Hyrcania was abandoned, only to be resettled during the Byzantine period, when a late-5th century monastery named Kastellion was established on the ruined fortress, which remained active until the early 9th century. There was a short-lived attempt by monks to rebuild in the 1920s–30s. The ancient ruins can still be seen today. Until the start of a 2023 archaeological campaign, the site had not yet been thoroughly excavated, and knowledge about the ruins of the site was based on a limited number of test pits.