One of the Seven World wonders?

The Oosterscheldekering in the Netherlands (see picture, a mechanical 8 km dam) is sometimes referred to as the eighth Wonder of the World, and has been declared as one of the modern Seven Wonders of the World by the American Society of Civil Engineers.

It's part of the Delta works, which embraced around 10.000 miles of dams, dikes, storm surge barriers, locks etc.

After the North Sea flood of 1953, a commission was installed which had to come up with a plan to research the causes and seek measures to prevent such disasters in future. They revised some of the old plans and came up with the so called "Deltaplan".

With the Chinese wall, the Delta works are the only two human made constructions in the world which can be seen from the Moon!