Near the town of Vlaardingen, remnants have been found of an ancient construction that probably served as a low levee. The construction was about 1 metre in height, at least 20 metres long, and consisted of a dual construction consisting of wooden piles and braided willow branches, that was subsequently filled with earth.
The levee was probably constructed over 2000 years ago, during the 2nd century BC. As such, it is probably the most ancient levee discovered so far in the Netherlands.
See https://nos.nl/artikel/2373863-mogelijk-oudste-dijkje-van-nederland-ontdekt-in-vlaardingen.html for some pictures.
Thanks Marcel, very interesting. I am very curious about the history of levees as we seem to know a lot more about old dams than about old levees. I would be interesting to learn more about this particular levee : can the date be made more precise (even with some estimated uncertainty), if this was used for flood protection, can we find a complete levee system (20 m of embankment can easily be bypassed (around), and finally was it used for agriculture (no need to retain water, only to slow it down).