Denver Sluice

is the hub of the water drainage system that protects a large area from flooding. It was engineered in the 1600s by Cornelius Vermuyden a Dutchman and funded by a group of Gentlemen Adventurers (forerunners of today's venture capitalists).

In short, subtle variations in land height in this flat area known as The Fens prevented water from draining to the sea. A new system of water channels at various heights and pumps (wind driven at the time) allowed water to be conducted away, further inland or to the North Sea.