The ruins atop Hyrcania have never been excavated, only surveyed. What we know about the site is the result of these surveys and ancient descriptions, particularly those of the first-century Jewish historian Josephus.
The square structure that dominates the height has its origins in the Hasmonean period (142–37 B.C.E.). The site is named for the Hasmonean ruler John Hyrcanus (134–104 B.C.E.), although he did not necessarily build the fortress. The fortress was rebuilt by Herod the Great (37–4 B.C.E.). In this, it is one of a series of defensive fortress/palaces in the Judean desert originally built in the Hasmonean period and rebuilt by Herod.
Hyrcania was abandoned after Rome suppressed the Great Jewish Revolt, destroyed Jerusalem and burned the Temple in 70 C.E. Beginning in the fifth century C.E. (the Byzantine period), Christian monks began to settle at the site, eventually building a monastery in the old, but now extensively remodeled, Hasmonean/Herodian fortress. The monastery took the name Castellion, “fortress” in Greek.
The outline of the square structure is still visible in this aerial photograph. Leading up 057to the summit is a switch-back trail ending at the remains of a tower that protected the monastery. The remains of the monastery tower can be seen more clearly in the photograph. A low stone monastery wall extends from the tower around the site, as can be seen in the aerial view. Below the right-hand stroke of the M-shaped path are the remains of the aqueduct, casting its shadow. Part of the aqueduct, which was fed only by runoff water from the occasional rain, can be seen close-up. The aqueduct did not proceed to the top of the mound, however, as there would be no way to get the water up the aqueduct. The water was stored in cisterns. Of the 21 cisterns on the site, six are on the summit. Presumably the water was hand-carried up there. Before reaching Hyrcania, the water was carried by two aqueducts, the longer of which extended over 5 miles.
One of Hyrcania’s larger cisterns is pictured with a man inside. The benches lining the walls led Joseph Patrich of Hebrew University, who performed the major survey of the site, to speculate that this might have been a swimming pool.
In the northeast part of the large rectangular structure on top of the site, the monks built a chapel, whose white mosaic floor is pictured. Elsewhere the monks used more colorful mosaics, such as that pictured here. The monks’ cells were sometimes decorated with frescoes that included the pictured cross.