Settlers initially put up with the marshy base because of the favourable waterways. Then in the 13th century, dykes were established along the Zuiderzee, the IJ bay (later to become a lake) and the estuary of the Amstel. The Amstel acquired a dam, so that the Amstel estuary, the current Damrak, became the small settlement’s first seaport. That settlement quickly grew into an important port where considerable international trade was conducted. This brought about unprecedented economic growth in the city.
A lack of space began to be felt as an increasing numbers of foreign traders moved into the area. The problem was exacerbated by the arrival of European citizens fleeing their homelands because of religious unrest and seeking safe refuge in Amsterdam. By the 16th century Amsterdam was bursting at the seams. The merchants who had become rich also wanted a larger and more spacious living environment. So at the end of the century, advanced plans were ready to bring about a considerable expansion of Amsterdam.