Living in a previously parted city is sometimes really strange. Everything is doubled: opera houses, universities (actually we've got 3 "real", and several other universities). But one of the strangest things is having two high towers in one city. The first one, the Funkturm, was build during the Weimar Republic, mainly for radio transmissions. But it was (and is) later also used by the arising television.
After the GDR built the Berlin Wall, East Berlin needed an own tower for transmissions. So the building of a tower in the south-eastern outskirts of Berlin began. Building a tower there was pretty efficient: It could stand on a small hill and no high buildings were around, so it hadn't be so high. Additionally towers are normally pretty ugly, so "hiding" a tower was clearly a good choice. But Walter Ulbricht, wasn't happy with this decision, so he gave the order to build a new tower together with the Palast der Republik (The Republic's Palace) at the Alexanderplatz. Being in the center of Berlin, the tower would now be visible from West Berlin. But if that's not enough, it was higher than the Funkturm. With the 365 m it had when it was finished 1969 (since 1996 it has even 368 m) it's more than twice the height of the Funkturm and on clear days and at the right spot, it is even visible from outside of Berlin!
Despite coming from West Berlin, I never visited the Funkturm. I do not not know why I never did, but I don't think I missed anything, as the tower is mainly surrounded by forest. But I will never forget my first visit of the Fernsehturm. It was 1989, I was 9 years old and the GDR still existed. Before 1989 visiting the GDR was complicated: If you were not just driving through (on special roads, so called Transitstrecken), you needed a good reason to go there. 1989 changed everything. Although I was so young, I clearly knew, that the GDR was finally coming to an end. One of the first lightenings was that citizens from the BRD (english: FRG) were allowed to visit the other part of the country. My mother, my sister and I, excited how the "other side" looked like, went to East Berlin. At the subway station Friedrichsstrasse, we left the West Berlin train, and went to the border control (that's defiantly very akward, border control on a subway station in the heart of a city!). The border control had two purposes: It should prevent people from the GDR to leave their country and people coming from the West had to exchange an amount of money from D-Mark to the so called Ostmark (East-Mark). The exchange rate was absurd: 1:1 had nothing in common with the real value of the Ostmark (even the during the unification of the currencies used exchange rate of 1:3 was ruinous for the BRD). After this my first contact with the GDR were its trains. They were more modern than the ones in the West: they had a red light and a acoustic signal, which showed that the trains are due to leave the station (a thing only introduced years later in West Berlin). But the rest was depressing. The people looked dull and the city stank from the exhaust gases of the Trabbis and the stoves (which still used brown coal).
The tower itself is a magnificent example of socialistic architecture. I admit, that one can refer to this kind of architecture as ugly, but together with the Palast der Republik, the world time clock, the Forum hotel, the Centrum warehouse and the fountain of peoples friendship (Brunnen der Völkerfreundschaft) it formed a great architectural composition around the Alexanderplatz. As a visitor of the tower one is at a height of 200-210 m in a sphere, which has two publicly accessible floors. On the first floor lies the viewing platform and above is a cafe. The Telecafe is really spectacular. You can not only eat and drink there pretty good, but you can see everything from one spot, as it rotates around its own axis. And the view is really great, maybe it's not the tower with the greatest distance view, but you can see all the great buildings of Berlin. The best thing I remember, is that I was unable to see the wall from there above. The city looked like one.
Finally some additional information from the towers website (http://www.berlinerfernsehturm.de). The tower is very easy to reach. I think the best way for tourists is just walking. Not far away from the tower are the Brandenburger Tor or the Berliner Dom and several other tourist attractions. So using the subway would just be a waste of time, money and experience. But if you really want to, just use the up to the station Alexanderplatz and you really can't miss the tower. Another possibility would be the bus line 100. This line is pretty good for tourists as it drives along the major attractions. The tower itself is opened from 9 am till 1 am during March and October and for the rest of the year from 10 am till midnight and the entrance is 6 Euro for adults and 3 Euro for under 16 year olds.