Generally, the side of a coin with the larger-scale image will be called the obverse (especially if the image is a single head) and, if that does not serve to distinguish them, the side that is more typical of a wide range of coins from that location will be called the obverse. Following this principle, in the most famous of ancient Greek coins, the tetradrachm of Athens, the obverse is the head of Athena and the reverse is her owl. Similar versions of these two images, both symbols of the state, were used on the Athenian coins for more than two centuries.