An
ancient fort created in the 2nd century
BCE and later expanded by the
Roman King Herod into a larger
citadel with
palaces,
defensive towers, and an
aquaduct system to supply
water. Masada was virtually
impregnable, as it rested on 7
hectares of space on a
mesa that towered 434 m above the
dead sea. After Herod died, the
Jewish Zealots (no, that's not a
slur, that was the actual name of the
sect) managed to take the
Romans by suprise and made the
fort their own.
Things stayed that way until about 70CE, when the Romans sacked Jerusalem, and were in the process of annihilating the remaining Hebrew resistance. The Romans managed to gain control of all Judea except for the garrison of 1000 men at Masada, which was proving to be a tough nut to crack. The only access to the fort at the time was along a winding trail on the side of the rock face, where any would-be attackers would be exposed to rocks, hot oil, and YHWH knows what else thrown down from above.
In the end, the Romans took a brute-force approach, and constructed a huge earthen ramp that led from the valley floor to the top of the mesa. Knowing their number was up, the Zealots took their own lives rather than become prisoners of the Romans. Only two women and five children who hid in the water tower survived to tell the tale.
Masada was later re-ocupied by Jews in the 2nd century CE, and later was the site of a Byzantine Church, which was abandoned in the 6th century. In the 20th century, the remains of Masada were surveyed and restored somewhat, and the locale is now a popular Israeli tourist attraction.
Thanks to britannica.com