Similar to the program I’ve seen in DC, these bikes are parked all around Berlin for folks to rent and explore the city. You register with Call-A-Bike online or by phone and they’ll give you an access code for the lock of a nearby bike. A 24-hour rental is quite inexpensive at $14 and when you’re done you just call and tell them where you left it. Berlin is the perfect city for biking, lovely intimate neighborhoods, no hills (that I saw) and bike lanes are pretty much everywhere. I’m definitely taking advantage on my next visit. The only downside is you’ll have to be on the continuous lookout for dumbass Americans like me who forget every ten minutes that many of the bike lanes are actually on the sidewalks, not the streets. “Joe, you’re in the bike lane. AGAIN.” (I nearly got clobbered about twenty times.) Berliners use their bike bells the way Manhattan’s cabbies lean on their horns. Good thing.