According to archaeology Professor Vassil Nikolov, citing evidence from work done at the Provadia-Solnitsata archaeological site (Bulgaria) in summer 2012, Europe's oldest urban settlement is near Provadia, a town located about 40km inland from Bulgarian city of Varna.

The team of archaeologists headed by Nikolov excavated stone walls estimated to date from 4700 to 4200 BCE. The walls are two metres thick and three metres high, and according to Nikolov are the earliest and most massive fortifications from European prehistory. Probably there were about 300 to 350 people living at the site in those times, living in two-storey houses and earning their living by salt mining.

Today Provadia is an important salt centre. Estimates are that salt has been extracted in the area for about 7500 years. Nikolov said that salt was the currency of ancient times, both in terms of value and prestige....