Friedrichstadt was an independent suburb of Berlin, and is now a historical neighbourhood of the city itself. The neighbourhood is named after the Prussian king Frederick I. Geography Friedrichstadt is located south of the Dorotheenstadt neighbourhood, and southwest of the historical suburb of Friedrichswerder. It is located south of the twin-city zone of Berlin and Cölln. Today, the northern part of the neighbourhood is located in the borough of Berlin-Mitte, while the southern part of the neighbourhood is located in borough of Friedrichshain-Kreuzberg. The border between the two boroughs runs along the southern side of Niederkirchnerstraße and Zimmerstraße. The official boundaries of Friedrichstadt extend from the Spittelmarkt starting between northbound streets Niederwall- and Oberwallstraße, along Behrenstraße west to Ebertstraße, and then south over the Potsdamer Platz, Stresemann- and Gitschiner Straße, ending at the Hallesches Tor, and then again north over Linden- and Axel-Springer-Straße, back to the Spittelmarkt. A large portion of the Spittelmarkt and adjoining Hausvogteiplatz were once part of a military installation associated with the historical suburb of Friedrichswerder. History After the death of prince-elector Frederick William of Brandenburg in 1688, his son, prince-elector Friedrich III, later king Frederick I of Prussia, was allowed to establish a new city on the outskirts of Cölln, one of the precursor cities of modern-day Berlin. In order to assist with the street layout and the placement of buildings and houses, various architects and engineers, including Johann Nering, Johann Behr, and Martin Grünberg were called in. The new city was founded in 1691. Friedrichstadt was the third expansion of the Berlin-Cölln city center, after Dorotheenstadt and Friedrichswerder. Friedrichstadt was built outside of the Berlin's fortifications, south of Dorotheenstadt and west of Friedrichswerder. However, the city was protected both by the militia of Leipzig and a lengthening of the western city wall of Dorotheenstadt. Today, this is the site of Mauerstraße (English: Wall Street). Toward the south, Friedrichstadt originally extended to the present-day Zimmerstraße. From that southern point, the city extended approximately to the fortifications of the city of Neu-Cölln. To enter the city from Friedrichswerder, one entered through the Leipziger Tor (English: Leipzig Gate), and to enter from Dorotheenstadt, one came through the Friedrichs-Tor. This new area of the city, however, was not referred to as Friedrichstadt until 1706, fifteen years after its founding. Friedrichstadt was designed with an unusually austere geometric style for the time, with broad streets which intersected at right