What Can You Open With a Key to the City?:
The tradition of conferring upon heroes and luminaries a key to the city dates back at least to medieval Europe. When a monarch or other ruler came to visit a town in his dominion, the city council would greet him at the gates and prepare a "joyous entrance," with flowers, dancing, singing, and so forth. The citizens would also present him with a key—probably a functional one—as a gesture of obedience but also, paradoxically, of autonomy. By offering a key, the citizens demonstrate that they have not been forced to grant the monarch entry and that they might have chosen not to. In medieval Europe, there was also a related custom of giving certain tradesmen preferred status so that they could enter a gated town on commercial business without first paying a toll.
As the New York Times pointed out Monday, there's a local tradition in New York of key-to-the-city recipients falling from grace. Baseball players Roger Clemens and Alex Rodriguez were both given keys (in June 2003 and August 2007 respectively), and both have since been accused of using performance-enhancing drugs. At least New York never honored a deposed tyrant. After donating several hundred thousand dollars to a Detroit church in 1979, Saddam Hussein received a key to the city.