It is situated near the Wesel-Datteln Canal , approx. It has about 90, people. The town adjoins in the north to the woodlands of the Haard and the natural park Hohe Mark. The northern town border coincides nearly completely with the course of the river Lippe. In the north Marl adjoins to Haltern am See , in the east to Oer-Erkenschwick , in the southeast to Recklinghausen , in the south to Herten , in the southwest to Gelsenkirchen and in the west to Dorsten.
The town area was already populated in the old and middle Stone Age, as many archeological finds in the district of Sinsen confirm. Remains of the first settlements are dated to BC. At BC Celtic tribes settled in the area but were expelled by invading Germanic tribes. The Brukterer controlled thereupon the area north of the river Lippe and the Marser lived south of the Lippe. The Germanic invasion was stopped by the advance of the Romans, who built a huge fort in Haltern.
Remains of a smaller Roman fort were found at the city limit between Polsum and Herten. After the Battle of the teutoburg forest in 9AC the Romans lost most of their influence and retreated behind the Rhine river. The area was again in Germanic possession. In 80 AC the Brukterer were expelled by rival tribes and moved to the today's area of Recklinghausen.
The next migration movement took place in the Marl area between the 5th and 7th century, when the Saxons invaded from the northeast across the Lippe into the former Brukterer area. In the th archeological excavations proofed, that the Brukterer built a circular hillfort in the district of Sinsen to defend against the Saxon attacks.
Today the hillfort is only recognisable for the expert and lies in the nature reserve "Die Burg" which means "the castle" which is named after the hillfort. Archeologists consider the hillfort as an outstanding historical monument which is worth of protection.
