Artemisium, properly a temple of Artemis (Diana), the name of several places in ancient geography. The most important of them was the promontory on the N. coast of Eubœa, off which the Greek ships fought with the fleet of Xerxes, almost simultaneously with the battle of Thermopylae, in 480 B. C. The success achieved here by the Greeks was soon followed by the great victory at Sal amis.