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Macau is an autonomous territory on the western side of the Pearl River estuary. Hong Kong lies about 64 kilometres to its east across the Delta. With a population of 650,900 living in an area of 30.5 km2 it is the most densely populated region in the world. A former Portuguese colony, it was returned to Chinese sovereignty on 20 December 1999.  It is known as the pre-eminent gambling capital of the world, dwarfing other gambling centers.

Macau was administered by the Portuguese Empire from the mid-16th century until late 1999, when it constituted the last remaining European colony in Asia. Portuguese traders first settled in Macau in the 1550s. In 1557, Macau was leased to Portugal from Ming China as a trading port. The Joint Declaration stipulates that Macau operate with a high degree of autonomy until at least 2049, fifty years after the transfer. Under the policy of "one country, two systems", China is responsible for military defense and foreign affairs while Macau maintains its own legal system, public security force, monetary system, customs policy and immigration policy. 

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