The grachtengordel (girdle of canals) that guards the Old Centre is idyllic, pleasant and quintessentially Amsterdam. A great way to explore them is by jumping aboard one of the many boat tours, which roam the waterways for an hour at a time. Singel was the medieval city moat; other canals such as Herengracht, Keizersgracht and Prinsengracht, which follow its line outwards, were part of a Golden Age renewal scheme for the rich. The connecting canals and streets, originally home to workers and artisans, have a number of cafés and shops. Smaller canals worth seeking out include Leliegracht, Bloemgracht, Egelantiersgracht, Spiegelgracht and Brouwersgracht.