Macau or Macao is a special administrative region of China. With a population of about 710,000 people and a land area of 32.9 km2 (12.7 sq mi), it is the most densely populated region in the world.
Formerly a Portuguese colony, the territory of Portuguese Macau was first leased to Portugal by the Ming dynasty as a trading post in 1557. Portugal paid an annual rent and administered the territory under Chinese sovereignty until 1887, when Portugal gained perpetual colonial rights with the signing of the Sino-Portuguese Treaty of Peking. The colony remained under Portuguese rule until the 1999 handover to China. Macau is a special administrative region of China, which maintains separate governing and economic systems from those of mainland China under the principle of "one country, two systems". The unique blend of Portuguese and Chinese architecture in the city's historic centre has resulted in its designation as a UNESCO World Heritage Site in 2005.
The gambling industry of Macau is seven times larger than that of Las Vegas. The city has one of the highest GDPs per capita and GDPs per capita by purchasing power parity in the world.
It has a very high Human Development Index of 0.925, as calculated by the Government of Macau, and the fourth-highest life expectancy in the world. The territory is highly urbanised, holding the status of the most densely populated territory on Earth; two-thirds of the total land area is built on land reclaimed from the sea.
Macau is located on China's southern coast, 60 km (37 mi) west of Hong Kong, on the western side of the Pearl River estuary. It is surrounded by the South China Sea in the east and south, and neighbours the Guangdong city of Zhuhai to the west and north. The territory consists of Macau Peninsula, Taipa, and Coloane. A 1 km2 (0.39 sq mi) parcel of land in neighbouring Hengqin island that hosts the University of Macau also falls under the regional government's jurisdiction. The territory's highest point is Coloane Alto, 170.6 m (560 ft) above sea level.
Urban development is concentrated on peninsular Macau, where most of the population lives. The peninsula was originally a separate island with hilly terrain, which gradually became a tombolo as a connecting sandbar formed over time. Both natural sedimentation and land reclamation expanded the area enough to support urban growth. Macau has tripled its land area in the last century, increasing from 10.28 km2 (3.97 sq mi) in the late 19th century to 32.9 km2 (12.7 sq mi) in 2018.