The capital of Azerbaijan is Baku, a city with a population of over two million people. It is located on the western coast of the Caspian Sea and is the largest city in the Caucasus region. Baku is an important cultural, economic, and political center in the region, and is home to many universities, museums, and other cultural institutions. It is also known for its oil and gas industry, which has made it one of the most prosperous cities in the region.