Spot the odd one out...

P! P! P! P!

About the random bikes: There was an entrance to the physics/chemistry building here. They decided that another entrence should become the main entrance. So they closed this one, removed all the bicycle racks and later, when they figured out the entrence was actually usefull.. this happens..

Order of events, as far as i know:
Close 'main' entrance, open backdoor pretending this is the main entrance.
Plan on remodeling backdoor to a real entrance.
Remove bicycle racks from former entrance.
Never cary out mentioned plan for backdoor.
Discover that the parkingspots are actually used.
Re-open former main entrance.
Wait for bike-madness.

Planning. its a skill.