From 27C3 public wiki
In front of the bcc - Photo by Thosch66
The Congress takes place at Berliner Congress Center (bcc) at Alexanderplatz (online map). The Alexanderplatz train station can be reached by S-Bahn, U-Bahn and regional trains. Check the page on Travel for more information.
The Berliner Congress Center is located southeast of Alexanderplatz. Leave the train station at exit "Alexanderplatz" and turn north, pass along the World Time Clock and proceed to the pedestrian crossing at Grunerstraße and cross Alexanderstraße afterwards. Then you stand in front of the bcc.
Interesting stuff nearby
Food near the Congress Center
Berliners: please fill this out w/ places hackers will find interesting!
The building is divided into three floors, named A, B and C - which are cellar, ground floor, and first floor, respectively:
Ebene/Floor A = "downstairs" = basement / cellar Ebene/Floor B = ground floor Ebene/Floor C = "upstairs" = first/upper floor
Floors B and C each provide a central room which is surrounded by a ring.
Floor B has another area attached which contains more rooms.
An elevator connects all floors.
An explanation of the various areas can be found on page Facilities.