Almost all popular sights of Berlin are located in the quarter "Berlin-Mitte" in the center of the city. If you want to do sightseeing in the summertime i recommend to rent a bike and just cycle around - like i did in this Video ;)

The itinerary shown in between can be found on the website mentioned below.
BTW: I rented a bicycle by using the "Call a Bike" system of the Deutsche Bahn (just Google for that for more informtion)
Have fun cycling through Berlin!

Music:
"Wednesday Morning" by slackstring
(http://www.musicalley.com/music/listeners/artistdetails.php?BandHash=e4967629e3ece2e3d6637a794654f79b)

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