The volcano-like profile of Herodium, founded by Herod the Great ca. 26 BCE, crowns the skyline south of Jerusalem. Following a review of the reports of explorers and itinerants who visited the site since the 15th century is a description of the discoveries made during the excavations at Lower Herodium in 1972, 1973, and 1978 * the pool complex, the large lower palace, the course and monumental buildings, the northern wing, and the roads, water systems, and boundaries of the site. The author, who is an architect and archaeologist, presents an exhaustive structural analysis of the mountain palace-fortress on the summit and a comprehensive discussion of the role, planning, and background of Greater Herodium. Contributions dealing with the pottery, inscriptions, frescoes, and coins are included in the report.