Berlin Fortress

The Berlin Fortress was the historic city fortification built in the 17th century to protect the districts of Alt-Berlin, Alt-Kölln, Neu-Kölln, and Friedrichswerder. Its construction came in the wake of the Thirty Years' War, which had devastated the region, and was planned under Elector Frederick William. The complex followed the then-modern bastion system, consisting of fortified earthen ramparts and flooded moats. While this structure offered protection against direct assaults, it quickly became obsolete as artillery advanced, since attackers could shell the city from a safe distance. Despite its military limitations, the fortress left a lasting mark on the cityscape. The eastern sections were completed between 1658 and 1662, while work on the western side dragged on until 1683 because of the difficult ground.

Today, almost nothing of the physical fortifications can be seen, as the ramparts were leveled starting in the 18th century and the moats were filled in during the 19th century. Even so, the historic structure is still clearly visible on the modern city map. The course of the streets, especially Unter den Linden and the route of the Stadtbahn, follows the lines of the former bastions and gates. You can find traces of the fortress in various places: Alexanderplatz takes the shape of the former ravelin in front of the Georgentor, while Köllnischer Park lies on the site of the seventh bastion. The Märkisches Museum, too, was deliberately built on this spot to evoke the city's history.

Some remnants still exist physically or have been documented by archaeologists. Beneath the office building on Jägerstraße, a section of the vaulted fortress moat survives as a restaurant cellar. The Mohrenkolonnaden, originally built over the Grüner Graben, stand at their original location, now surrounded by buildings of the Federal Ministry of Justice and Humboldt University. In addition, the slightly offset course of Unter den Linden still reveals the location of the former Neustädtisches Tor. These relics and the traced street layout make the invisible fortress something that attentive tour guides and historians can bring to life.