Maeslantkering

One of the biggest moving structures in the world, the Maeslantkering is a storm surge barrier protecting the port city of Rotterdam. The huge machine consists of two large arms on each side of the waterway that can float into position and then be submerged. It's the sheer size of the arms that makes Maeslantkering so impressive: Each is almost 800 feet long (more than 200 feet taller than the Washington Monument), and is connected to the mainland with the world's largest ball joints, each more than 30 feet in diameter.

The barrier was completed in 1997 after several years of construction, as part of a large-scale infrastructural project embarked on by the Dutch government, conceived as a way of restructuring the entire coastline along the Rhine Delta. Most of the population of the Netherlands lives on or around this delta, and the so-called low country is dependent on a complex system of infrastructure to maintain sea levels and contain waterways. 

The project involved the building of dams, dikes, storm barriers, levees, and other such structures. One look at the Maeslantkering and the scale of this infrastructure is obvious. With its gigantic moving parts and vast span, it is truly a technological marvel. Those interested can learn more about the structure by visiting the nearby Technology Museum at the Keringhuis.