ABSTRACT
IT is probable that at the beginning of the twelfth century Amsterdam was formed as a small settlement of ftshermen and merchants where the river Amstel flows into the Y, a deep arm of the former Zuiderzee (now Yssellake). Since olden times the citizens of Amsterdam have been confronted with the problem of the all-surrounding water. The fust inhabitants canalized the Amstel by building a dam about a quarter of a mile from its mouth. That is why the settlement was called Amstel-dam. At the same time they constructed a dam along the banks of the Amstel and furthermore along the Y and the Zuiderzee, thus protecting the hinterland against tidal waves.
