Initially Vlooienburg was located right besides the new city wall. It was therefore a neigbourhood on the edge of the city. This would however change rapidly in the course of the 17th century, as new zones were soon occupied on the other side of the the city wall. It was ultimately demolished in 1663 when the defenses had been relocated again.
This is very much a simplified representation of the defensive system, which would have featured more levels, and various built structures. The image below shows a more accurate cross-section of its construction. Parts of the bastion nearest to Vlooienburg have been archaeologically investigated by the municipial archaeological unit (Jayasena 2023). It showed it was built up from city refuse, sand and sods. A revetment wall made of heavy oak timbers was made to keep the earth mass into place.