An "exceptional" tomb from the fifth century BC, likely that of a Celtic prince, has been unearthed in a small French town, shedding light on Iron Age European trade, researchers said Wednesday. The grave, crammed with Greek and possibly Etruscan artefacts, was discovered in a business zone on the outskirts of Lavau in France's Champagne region, said the National Archaeological Research Institute, Inrap. A team from the institute has been excavating the site since October last year, and have dated it to the end of the First Iron Age -- a period characterised by the widespread use of the metal....