The Gate of all Nations (Gate of Xerxes) at Persepolis, a 2500-year old World Heritage Site of ancient Persian palaces and temples near Shiraz in southern Iran. Persepolis was the ceremonial capital of the Persian Empire during the Achaemenid dynasty. At the height of its power, the Achaemenid Empire encompassed about 7.7 million square kilometers and spanned three continents, as far west as Libya to nearly all Middle East, and to Central Asia. On the Xerxes gate there is a pair of Lamassus, bulls with the heads of bearded men. Another pair, with wings and Persian head stands on another side of the gate.