Abu Dhabi is the capital and the second-most populous city of the United Arab Emirates, it is also the capital of the Emirate of Abu Dhabi. The city of Abu Dhabi is located on an island in the Persian Gulf, off the Central West Coast. Most of the city and the Emirate reside on the mainland connected to the rest of the country. As of 2021, Abu Dhabi's urban area had an estimated population of 1.5 million, out of 2.9 million in the emirate of Abu Dhabi, as of 2016. The Abu Dhabi Investment Authority is headquartered in the city, and was the world's 5th largest sovereign wealth fund in 2021. Abu Dhabi itself has over a trillion US dollars worth of assets under management in a combination of various sovereign wealth funds headquartered there.