This is the Maastunnel.
Back to Dijkzigt.
The Maastunnel connects the banks of the Nieuwe Maas. It's 1.3 kilometres long, building commenced in 1937 and finished in 1942. There was no official opening ceremony, but the Dutch held an unofficial opening ceremony in secret without Nazi participation.
In 1944 the German invaders placed explosives in the tunnel so they could destroy it at a moment's notice. Perhaps due to the sabotage of the detonators (the overhead lines) by the Dutch resistance the explosives were not detonated.
What's really cool is that there are three tunnels stacked on top of each other with the car tunnel being the highest, then the moped/bicycle tunnel and the pedestrian tunnel being the very lowest. You go down to them using very old, steep, wooden escalators and then a spiral staircase to the pedestrian tunnel. But being lazy, I always walked down the moped/bicycle tunnel.
