The exhibition is rich in similar moments of revelation - a 1st Century mask and helmet found by metal detection in a field in Britain two years ago and a 4th Century BC head of a king unearthed in a tomb in Bulgaria in 2004, the face so lifelike and belligerent that it makes you want to run for cover. It also has historians of the early Hellenistic period re-evaluating the level of artistry in Thracian culture.