A 4,000-year-old map of Europe is Saint-Belec slate, was found in northwestern France more than 100 years ago, but it was forgotten until 2014.
Analysis of local hydrography and location of ancient architectural monuments (in particular megaliths) allowed scientists to estimate scale of map - it covers an area of 630 km2.
Scientists have made several archaeological discoveries using this map. Weight of plate is 1.5-2 tons, length is 2m, width is 1.5m, thickness is 15cm.