,1963 The former Mitte district had been established by the 1920
Greater Berlin Act and comprised large parts of the historic city around
Alt-Berlin and
Cölln. Brandenburg Gate was the western exit at the Berlin city boundary until 1861. Between 1961 and 1990, the area's East Berlin portion was surrounded by the
Berlin Wall on the north, south and west. There were some border control points, the most notable of which was
Checkpoint Charlie between
Kreuzberg and Mitte, which was operated by the
United States Army and was open to foreigners and diplomats. Two other checkpoints were at Heinrich-Heine-Straße/
Prinzenstraße east of Checkpoint Charlie, open to citizens of West Germany and West Berlin and on
Invalidenstraße in the north on the border with the West Berlin Tiergarten district (the present-day
Moabit locality). == Regierungsviertel (Government District) ==