Tanais (
Tánaïs; ) was an
ancient Greek city in the
Don river delta, called the
Maeotian marshes in
classical antiquity. The delta reaches into the northeasternmost part of the
Sea of Azov, which the Greeks called
Lake Maeotis. The site of ancient Tanais is about 30 km west of modern
Rostov on Don. The central city site lies on a plateau with a difference up to 20m in elevation in the south. It is bordered by a natural valley to the east, and an artificial ditch to the west.