At the beginning of the 19th century, the Alexander-platz was one of the busiest squares in the city.
Ox Market
Originally the square was called the Ochsenmarkt or ox market, but after a visit by Tzar Alexander I it was renamed to Alexanderplatz. The locals simply call this large square ‘Alex’.
Socialist Architecture
Most of the buildings on the square were destroyed by bombing during the second world war. As the center of East-Berlin, the square was used as a showcase of socialist architecture. This resulted in some plain bulky buildings and a huge television tower.
Fernsehturm
The TV tower, known as the Fernsehturm or the Tele-spargel (toothpick) is one of the largest structures in Europe. The total length to the top of the spire is 365m or 1197 ft. 
It was built in 1969 by a team of architects with the help of Swedish experts. It contains a concrete shaft, a steel-cladded metal sphere and a TV antenna. The sphere contains a revolving restaurant (Telecafé) at 207m and a viewing platform at a height of 203m.
Monuments
In 1969 two more monuments were added to the square, the Weltzeituhr (World Time Clock) by Erich John and the Fountain of International Friendship.
Redevelopment
The square is known to be one of the least attractive from an architectural point of view, so the city of Berlin commissioned an architectural competition which was won by Hans Kohlhoff (also one of the architects of the modern Potsdamer Platz). The plan involves the construction of several modern high-rise buildings.