The Aras (Araks or Araxes) River forms the border between Turkey, Armenia, Azerbaijan, and Iran and is one of the largest rivers of the Caucasus.
The area around the Aras has been a hotbed of geopolitical turmoil for millennia. Persians have fought battles in this region against the Romans, Turks and more recently the Russians.
In the 1990's there were significant hostilities along this border between Azerbaijan and Armenia after the collapse of the Soviet Union.
The Aras Dam on the Aras River is on the border of Iran and the Nakhchivan Autonomous Republic which is part of Azerbaijan.
The Nakhchivan Autonomous Republic is one of those interesting consequences of geopolitical events (such as the Wakhan Corridor in Afghanistan). Nakhchivan is a landlocked exclave of the Republic of Azerbaijan. That is to say it is physically cut off from the other part of Azerbaijan by Armenia.
There is a good view of Mt Ararat across the waters of the Aras Dam.