Solnitsata

Prehistoric proto-city (4700–4200 BC) near Provadia, Bulgaria, Solnitsata is the oldest salt production center in continental Europe and the first urban center in prehistoric Europe. This fortified stone settlement featured a citadel, inner and outer city, and pottery production. Massive stone walls protected salt—a commodity worth more than gold in antiquity. Despite an estimated population of only 350, archaeologist Vassil Nikolov argues it meets criteria as a prehistoric proto-city. [1][2]