Amsterdam has three semi-circular canals (and by an odd coincidence, so do you — in your ears).  As a result, boats proliferate in this charming city, and bikes even more so.  There are more bikes than people in Amsterdam.  I'm not sure why, except that they are an excellent and inexpensive way to get around the town.

Behind the canal boat in this image is a parking lot for bikes.  It's the only way to keep them from cluttering up the streets.

Because of its layout, a canal boat tour is great way to see Amsterdam.  It provides a comprehensive view of the wide variety of canal-front housing and a relaxing hour-long break from the noise of the city.  For a first-time visitor, the guide's description of the passing scene is an excellent introduction to a charming town.