Wikipedia
Solnitsata (, "The Saltworks") was an ancient town located in present-day Bulgaria, near the modern city of Provadia. Believed by Bulgarian archaeologists to be the oldest town in Europe, Solnitsata was the site of a salt production facility approximately six millennia ago; it flourished ca 4700-4200 BC. The settlement was walled to protect the salt, a crucial commodity in antiquity. Although its population has been estimated at only 350, archaeologist Vassil Nikolov argues that it meets established criteria as a prehistoric city.
Salt production drove Solnitsata's economy, and the town is believed to have supplied salt throughout the Balkans. A large collection of gold objects nearby has led archaeologists to speculate that this trade resulted in considerable wealth for the town's residents.
The town is believed to have been destroyed by an earthquake.