Real estate prices have surged, and local shops are making way for tourist-oriented ones, making the centre unaffordable for the city's inhabitants. These developments have evoked comparisons with Venice, a city thought to be overwhelmed by the tourist influx. Construction of a metro line connecting the part of the city north of the river (or lake) IJ to the centre was started in 2003. The project was controversial because its cost had exceeded its budget by a factor three by 2008, because of fears of damage to buildings in the centre, and because construction had to be halted and restarted multiple times. The metro line was completed in 2018. Since 2014, renewed focus has been given to urban regeneration and renewal, especially in areas directly bordering the city centre, such as Frederik Hendrikbuurt. This urban renewal and expansion of the traditional centre of the city—with the construction on artificial islands of the new eastern IJburg neighbourhood—is part of the Structural Vision Amsterdam 2040 initiative. Amsterdam is located in the Western Netherlands, in the province of North Holland, although it is not its capital which is Haarlem. The river Amstel ends in the city centre and connects to a large number of canals that eventually terminate in the IJ. Amsterdam is about below sea level. The surrounding land is flat as it is formed of large polders. A man-made forest, Amsterdamse Bos, is in the southwest. Amsterdam is connected to the North Sea through the long North Sea Canal. Amsterdam is intensely urbanised, as is the Amsterdam metropolitan area surrounding the city. Comprising of land, the city proper has 4,457 inhabitants per km2 and 2,275 houses per km2. Parks and nature reserves make up 12% of Amsterdam's land area. Amsterdam has more than of canals, most of which are navigable by boat. The city's three main canals are the Prinsengracht, Herengracht, and Keizersgracht. In the Middle Ages, Amsterdam was surrounded by a moat, called the Singel, which now forms the innermost ring in the city, and gives the city centre a horseshoe shape. The city is also served by a seaport. It has been compared with Venice, due to its division into about 90 islands, which are linked by more than 1,200 bridges. Amsterdam has an oceanic climate (Köppen "Cfb") strongly influenced by its proximity to the North Sea to the west, with prevailing westerly winds.