During the late 2nd millennium B.C. in the Bronze Age, a special type of defensive structure known as nuraghi (for which no parallel exists anywhere else in the world) developed on the island of Sardinia. The complex consists of circular defensive towers in the form of truncated cones built of dressed stone, with corbel-vaulted internal chambers. The complex at Barumini, which was extended and reinforced in the first half of the 1st millennium under Carthaginian pressure, is the finest and most complete example of this remarkable form of prehistoric architecture.

Źródło: World Heritage Convention
http://whc.unesco.org/en/list/833