Neolithic Jericho (Tell es-Sultan) marks a leap in structural scale: the move from the individual dwelling to a collective structure enclosing an entire settlement.

The wall ringing the site was built of mortarless dry-stone masonry; surviving sections show a thickness of roughly 1.8 metres and considerable height. Set immediately inside and abutting it rises a cylindrical stone tower — about 8.5 metres across, with a surviving height of some 8 metres. The tower is not solid: a narrow stone staircase of twenty-two steps runs up through its body to the top. This is among the earliest known monolithic stone structures with internal circulation; the stair is buried within the mass so that structural continuity is preserved.

The wall's purpose is debated. The classic reading is military defence; newer interpretations cast the wall as a barrier against floods and mudflows and the tower as a ceremonial or astronomical marker. Architecturally the decisive point is independent of function: for the first time people designed and built a single structure far beyond the scale of individual shelter — as a thick, continuous, load-bearing mass of masonry. This moment, in which stacked stone produces not just a wall but mass and volume, is the structural seed of the later tradition of forts, ramparts, and towers.