CTESIPHON, in Ancient Geography, a large village, or rather a fine city, of Chalonitis, the most southern province of Assyria. It was situated on the left or east side of the Tigris, opposite to Seleucia on this side; and built by the Parthians, to rival Seleucia. Here the kings of Parthia passed the winter (Strabo); as they did the summer at Ecbatana.