because of bad sanitation in the old city. Before this relaxation, the historic centre of Copenhagen was inhabited by approximately 125,000 people, peaking in the census of 1870 (140,000); today the figure is around 25,000. In 1901, Copenhagen expanded further, incorporating communities with 40,000 people, and in the process making Frederiksberg an enclave within Copenhagen. Since the summer 2000, the cities of Copenhagen and Malmö have been connected by a toll bridge/tunnel (Øresund Bridge) for both rail and road traffic. As a result, Copenhagen has become the centre of a larger metropolitan area which spans both nations. The construction of the bridge has effected many changes to the public transportation system and the extensive redevelopment of Amager, south of the main city. First settlements Signs of human activity dating back to about 4000 BCE have been found, but there are no signs of permanent settlements from that time. Archaeological excavations indicate that the first town dates back to the 11th century and consisted of two settlements, one in the western part of the medieval city encircled by what are now the streets of Mikkel Bryggersgade, Vestergade, Gammeltorv/Nytorv and Løngangsstræde, roughly corresponding to the coastline of the time, and another smaller settlement at what is now Kongens Nytorv. The surrounding area consisted of moist beach meadows and signs of cattle grazing have been found. The city probably had a harbour located at present day Højbro Plads. Details of the existence of a small town as early as the 11th century have recently been published by Videnskab.dk with a series of articles documenting new archeological finds. These provide evidence of a large estate at today's Kongens Nytorv, a church close to the later St Clemens, a market, at least two wells and many smaller habitations spread over a fairly wide area. Absalon's town In the 12th century Copenhagen assumed increasing importance and the town was reinforced with earthworks. The Roman Catholic Church erected cathedrals in Roskilde and in Lund (in what is now Sweden), which laid the basis for further development in those regional centres. As Copenhagen was midway between the two cities, it was centrally located for traffic and trading. The earliest written mention of the town dates back to the 12th century, when Saxo Grammaticus in Gesta Danorum refers to it as Portus Mercatorum, which translates into Merchants' Harbour or in the Danish of the time Købmannahavn. In a letter