If you go back to Venice on Sly 3, you may notice the coffee house near the police station is inacsessable. This is not true, if you know where to look.

Walk up to the front entrance of the police station(the vent on top has been boarded up), and you'll see an interaction symbol.

Hit the circle button to open the door. Instead of opening the door, the camera will zoom across the plaza and open the coffeehouse door. When the room loads, you will be in the coffeehouse! Not useless, and fun.