What is the oldest and southernmost city in Russia, with 7 miles of city wall?

Question

Murmansk, a Russian city which is consolidating a focus on resources for oil and gas exploration and transport, is on the shores of what body of water?

Answer 1

Derbent , formerly romanized as Derbend, is a city in the Republic of Dagestan, Russia, located on the Caspian Sea, north of the Azerbaijani border. It is the SOUTHERNMOST city in Russia, and it is the second-most important city of Dagestan

To the south lies the seaward extremity of the Caucasian wall otherwise known as Alexander's Wall, blocking the narrow pass of the Iron Gate or Caspian Gates.