Which capital city is the lowest in elevation on Earth?

Baku, Azerbaijan, is the lowest national capital city in the world, standing about 28 metres below sea level. The city occupies the southern shore of the Absheron Peninsula beside the Caspian Sea.

Baku's unusual elevation is connected to the Caspian Sea basin, whose water level lies below global mean sea level. The city is also Azerbaijan's largest urban centre and a major port, commercial hub, and cultural centre in the Caucasus region.

The question refers to a national capital, not necessarily the lowest point in any capital's wider metropolitan area. That distinction helps avoid confusion with cities such as Amsterdam, Jakarta, or Copenhagen, parts of which are low-lying but do not sit as far below sea level as Baku.

Baku's location helped shape its history. Petroleum seeps around the Absheron Peninsula were known for centuries, and large-scale oil production transformed the city during the nineteenth and early twentieth centuries. Today, Baku is also known for landmarks such as the Walled City, the Maiden Tower, and the Flame Towers.