[1]: 32–33 The oppidum was located on a plateau of c. 97 hectares (240 acres), around 200 metres (660 ft) above the valley floor, surrounded by steep cliffs in every direction except at the eastern and western extremities.[1]: 32 It was protected by a wall (murus gallicus) enclosing an area of up to 140 hectares (350 acres), pierced by at least two pincer gates and in 52 BC it possibly had a population of 80,000, including refugees and men under the command of Vercingetorix.The remains of siege rings said to match Caesar’s descriptions have been identified by archaeologists using aerial photography (e.g. by René Goguey [fr]).Franco-German excavations led by Michel Reddé [fr] and Siegmar von Schnurbein [de] from 1991–97 confirmed these findings and effectively ended the long debate among archaeologists about the location of Alesia.In the 1960s, a French archaeologist, André Berthier [fr], proposed that the location of Alesia is at Chaux-des-Crotenay in Franche-Comté, at the gate of the Jura mountains—a place that better suits the descriptions in Caesar's Gallic Wars[4]—and indeed, Roman fortifications have been found at that site.