The historic city centre is a prominent World Heritage Site of UNESCO. Bruges got its city charter on July 27, 1128 and new walls and canals were built. Since about 1050, gradual silting had caused the city to lose its direct access to the sea. A storm in 1134, however, re-established this access, through the creation of a natural channel at the Zwin. The new sea arm stretched all the way to Damme, a city that became the commercial outpost for Bruges. The area of the whole city amounts to more than 13,840 hectares, including 1,075 hectares off the coast, at Zeebrugge (meaning "Brugge aan Zee" or "Bruges on Sea"). The city's total population is 117,073 (1 January 2008), of which around 20,000 live in the historic centre. The metropolitan area, including the outer commuter zone, covers an area of 616 km² and has a total of 255,844 inhabitants as of 1 January 2008.