An army of windmills.

When the hand-dug canals reached their drainage limits in the early 1700s, and the river levels became too high to allow the canals to drain the surrounding area, a series of windmills were built to raise the water, step by step, to river level.

What resulted was this fantastic example, where you can see how polders worked, how windmill pumps worked, and some amazingly well preserved Dutch ingenuity.

Kinderdijk is a UNESCO world heritage site, now below sea level, and no longer using the windmills. They are now preserved as a historic record of Dutch achievement.

The name, meaning "child's dike" comes from the legend relating to the 1421 flooding here, where a baby in a cradle was kept afloat in the flood water by a cat that balanced the cradle to stop water from filling it (the origin of the "cat and the cradle" story).