A city bike tour is a must and will show interested stag parties everything from majestic old buildings to the ultra modern glass and steel architecture of Potsdamerplatz.
Berlin is blessedly flat so you won't break a sweat going from Brandenburg Gate to Checkpoint Charlie. If that doesn't grab you, the beer most certainly will! Beer is a massive part of German culture so make like a local, order litre steins, bratwurst and giant pretzels and join the party.
