Feats of engineering
Due to the successive city enlargements there are differences in water levels within the city. When the canals were originally constructed, at the same time an ingenious system of locks and bridges was devised. Locks actually ensure that the differences in levels can be overcome, while the many permanent or movable bridges ensure unhindered passage for both land and water traffic.
Early waste management
The water in the canals needs to be refreshed regularly. These days water is pumped in through the locks from the Ijsselmeer. Previously there was a dependence on the tides in the IJ, which connects directly with the Zuiderzee. But because the canals were used as open drains in those days, the stench will often have been unbearable. To at least combat pollution through household waste, a municipal rubbish collection service was actually set up as far back as the 17th century, using barges on the canals. Right to this day a municipal service clears floating rubbish from the water.