Tanais was an ancient Greek city in the Don river delta, called the Maeotian marshes in classical antiquity. It was a bishopric as Tana and remains a Latin Catholic titular see as Tanais.
The archaeological park of Tanais. May 2017
Relief from Tanais
The Don is the fifth-longest river in Europe. Flowing from Central Russia to the Sea of Azov in Southern Russia, it is one of Russia's largest rivers and played an important role for traders from the Byzantine Empire.
The Don in Voronezh Oblast.
Don river in Voronezh Oblast
Source of the Don in Novomoskovsk, Tula Oblast