The Delta works are humungous dams that raise and lower to let the water in and out of a group of rivers that empty into the North Sea in southwestern Netherlands, near Middleburg. They were built because of a big flood in 1953. After that flood the people decided they needed a way to protect their land, but they also didn't want to damage the ecosystem by permanently closing the rivers off. To build the dams, engineers first put down mats on the bottom of the sea. They also compacted the sand using a large vibrating machine. To see how the project was going, they used an underwater camera. When you visit the Delta works, be sure to take time to play at the waterland, which is a kind of wet playground. There is also a film about the construction which shows how incredibly impressive this project was. The town of Middleburg is also really pretty, with a great Stadhuis (city hall).
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