Sneek is built around a waterway (in old documents called the Magna Fossa) The waterway to the north (Geeuw, Sneeker Oudvaart)( was needed because the Middelzee was silted. The old hemdijk comes in as the "Hemdijk", turns into the "Oude Dijk" and becomes the "Wijde en Nauwe Noorderhornes" before it goes on as the "Peperstraat" and the "Wijde en Nauwe Burgstraten", it is eventually the base of the busy shoppingstreet the "Oosterdijk", and leaves the city as the "Griene Dyk".

Sneek received several city rights in the 13th century, which became official in 1456. Sneek was now one of the eleven Frisian cities. This was also the beginning of a blooming trading city that would last until the year 1550. In 1492 they began building a ditch and wall around the city. In those days Sneek was the only city in Friesland that had a wall. Only the waterpoort (watergate) and the Bolwerk are remaining today.

In this panorama of the Dutch photographer Hans Molenkamp you can see the 'Waterpoort' with it's remarkable towers in the center of the image.

http://en.wikipedia.org/wiki/Sneek