Baku is the capital and largest city of Azerbaijan, as well as the largest city on the Caspian Sea and of the Caucasus region. Baku is located 28 metres (92 ft) below sea level, which makes it the lowest lying national capital in the world and also the largest city in the world located below sea level. The city is the scientific, cultural and industrial center of Azerbaijan. Many sizeable Azerbaijani institutions have their headquarters there, including SOCAR, one of the world's top 100 companies. The city is renowned for its harsh winds. This is reflected in the city's nickname, the "City of Winds." Summers are hot and humid, winters cool, wet and breezy.