For a long time the Alexanderplatz, the largest square in Berlin, was one of the main landmarks of the East Berlin in the period of GDR. Since the 18 century it had been a common market square, and it was so called in honor of the Russian Emperor Alexander I, who visited Berlin in 1805.
The main sights of the Alexanderplatz are the World Time Clock Tower and the Fountain of Friendship between Peoples (do not confuse with the Neptune Fountain). Also in 1969 on the Alexanderplatz there was erected a TV tower 368 meters high. You can ascend onto a viewing platform to see Berlin from above.