Berlin has a great history so you can visit many interesting sites. Rent your car at the airport in Berlin and enjoy this great city.
The main attractions of the city are: the Brandenburg Gate, a triumph of peace over war, the Berlin Wall was torn down in the 90s, the Berlin Cathedral, the German parliament and Berliner underweltwen, an association performing tours through the underground city.
There are many museums but essential are: the Pergamon Museum and the new museum housing collections and works amazing.
To stroll through the city you can get close to the squares and streets of Unter den Linden, which is the main street of Berlin Kurfürstendamm or Potsdamer Platz areas where you can stroll and shop.
If you still have time you can visit places like the Tower televison Berlin is the highest in Germany with 368 meter high building, the Charlottenburg Palace or Tacheles considered the most famous alternative cultural center in Berlin.
There many bars and restaurants to dine in. German food is know for being simple and yet very rich. The main dishes to try are: Currywurst: chopped sausage with curry sauce, Kasseler: smoked pork ribs, Apfelkuchen: apple pie or Käsekuchen: cheesecake.
In short, Berlin is an open, modern and busy capital. Come to this city and enjoy the city.