Canals and dykes are a common sight in the Netherlands. They are used not only to keep the land from being completely unusable, but also for security. I took this picture at the Bourtange Fortress, which was used to protect the area to the west from invasion from the east. The stronghold is laid out in the shape of a star. So in order for someone to invade they had to not only cross a set of double canals but as they approached they could be fired at from two sides due to the shape of the dykes. I saw an aerial photo of the area and couldn't believe how perfectly shaped it was even though it was built long before the invention of laser and satellite and other technology that would help to design such a structure.