Maastunnel. Rotterdam, Netherlands

The Maastunnel, opened in 1942, is the oldest submerged tunnel in the Netherlands. It is a vital artery beneath the Nieuwe Maas River in Rotterdam. Designed with four separate tubes—for cars, cyclists, and pedestrians—it was the first underwater tunnel in the world built using a rectangular immersed-tube method.

Maastunnel is more than just a piece of engineering history: it played a quiet role during WWII, opening in secret without Nazi participation. Today, its iconic ventilation towers and original wooden escalators remain part of the city’s living heritage.

A major restoration completed in recent years brought the tunnel back to its original appearance, with yellow asphalt, natural stone bands, and soft LED lighting — preserving the past while upgrading for the future.