TOP OF THE WORLD. Two hundred feet in diameter, the circular seven-story palatial fortress on top of Herodium was encircled by two concentric walls. After the artificial cone-shaped fill of Herodium was constructed, only two-thirds of the 100-foot-tall building was visible above ground. While the eastern half of the structure consisted of a courtyard enclosed by a peristyle (columned porch), the western half was comprised of living quarters and other various rooms. Around its perimeter, the fortress had four towers.