The Maeslant weir in Rotterdam was built from 1991 to 1997. It protects about 1 Millon people against a storm flood in the metropolitan area Rotterdam.
There is an arc-shaped gate on both shores of the Meuse. In case of impending storm flood the semicircular gates swing and close the harbor entrance to Rotterdam.
The dimensions are enormous: The swivel joint is 10m in diameter, the entrance is 360m wide.