Flevum

Two Roman fortifications (usually called Flevum I and Flevum II) have been discovered at the mouth of actual North Sea Canal: the first was initially a small marching camp made by Tiberius (similar to the nearby Ermelo fortification built in 4 AD), and later enlarged to be a castrum and a port by Germanicus around 14 AD.

It controlled an important watercourse, the Oer-IJ, the northernmost outlet of the river Rhine, and an exit of Lake Flevo.

This harbor gate gave access to a short open jetty where larger ships could be loaded and unloaded so they would not have to be pulled into the countryside.

These slipways, approximately 6 m wide, could contain galleys over 30 m long...the first shipshed was built in the western part of the (Flevum) fort, at a short distance from the shore.

It lay so close to the river, that the above-mentioned scouring overwhelmed, or washed away, part of it...(then) the shipshed was moved some 30 m southwards.