Maastunnel traffic tunnels

thumb|210px|Euromast and Maastunnel ventilation (centre) thumb|right|210px|Cyclist section of the Maastunnel thumb|right|210px|Pedestrian section of the Maastunnel thumb|right|210px|Cross-section of the tunnel from :File:TUNNELBOUW-PGM4011510.webm|a 1938 video (full video on Commons) The Maastunnel is a tunnel in Rotterdam, the Netherlands, connecting the banks of the Nieuwe Maas. About 75,000 motor vehicles and a large number of cyclists and pedestrians use the tunnel daily, making the Maastunnel an important part of Rotterdam's road network. 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.

Construction of the tunnel was preceded by years of animated discussions. Although there was agreement as to the need for a new permanent connection between the two banks of the Nieuwe Maas, there was lack of agreement as to whether it should be a bridge or a tunnel. A tunnel proved to be more attractive financially than a bridge, largely because of the great height a bridge would have needed to avoid hindering the passage of ships from the port of Rotterdam, the largest port in Europe.