Azerbaijan's capital is Baku, a four-letter word. Baku is the largest city in Azerbaijan and the Caucasus region, located on the southern shore of the Absheron Peninsula on the Caspian Sea. It is the cultural, scientific, and industrial center of the country. Baku has a long history, having been inhabited since the 8th century BC. It was the capital of the Shirvanshah state in the 15th century and later became part of the Russian Empire in 1806. After the fall of the Soviet Union, Baku became the capital of the newly independent Republic of Azerbaijan in 1991.