Caesarea Mazaca (mod. Kaisarieh), is an ancient town of Asia Minor which served as the residence of the kings of Cappadocia. Its geographical situation has made it a place of commercial importance throughout history. It lay on the ancient trade route from Sinope to the Euphrates, on the Persian Royal Road from Sardis to Susa, and on the great Roman highway from Ephesus to the East
Thought to be named Caesarea by Claudius, it stood on a low spur on the north side of Erjies Dagh (Mons Argaeus). The site, now called Eskishehr, shows only a few traces of the old town. It was destroyed by the Sassanid king Shapur I of Persia (Sapor) after he he had defeated Valerian in A.D. 260. At this time it was stated to have contained 400,000 inhabitants. In the 4th century A.D., the bishop Basil established an ecclesiastical centre on the plain, about one mile to the northeast which gradually supplanted the old town. A portion of Basil's new city was surrounded with strong walls and turned into a fortress by Justinian.
Within the walls, lies the greater part of Kaisarieh rebuilt in the 13th and 16th centuries. The town was captured by the Seljuk sultan, Alp Arslan, 1064 and by the Mongols, 1243, before passing to the Osmanli Turks. .