A gold 20-stater depicting Eucratides I, the Greco-Bactrian King who reigned from c. 171 to 145 BC. The largest known gold coin from antiquity, it weighs 169.2 grams and has a diameter of 58 mm. Originally found in Bukhara, and later acquired by Napoleon III, it is now held at the Cabinet des Médailles, Paris.Photograph: National Library of France