The mouth of the Don River has been of great commercial and cultural importance since the ancient times. It was the site of the Greek colony Tanais, of the Genoese fort Tana, and of the Turkish fortress Azak.
Rostov-on-Don was founded on December 15, 1749, as a customs house was set up on the Temernik River (a tributary of the Don) to control the trade with Turkey. The custom house was built according to the edict of the Empress Elizabeth, the daughter of Peter the Great. Not far from the customhouse grew the fortress. It was named after Russian metropolitan, Saint Dimitry of Rostov, a newly-glorified bishop from the old Northern town of Rostov the Great.