Away from the main mission there are side-quests in the form of Borgia towers, which players can choose to infiltrate before killing the leader inside and burning the structure to the ground.
In true AC style, you'll always reach the top of these towers before setting them alight and getting to the bottom again with a graceful swan-dive, the flames licking at your rapidly descending heels.
And here's something we didn't expect to be revealed at all until you played the game yourself...
Ubisoft seem more than happy t talk about and show off the fact that there's going to be a pretty major face-off between Ezio and Cesare in Spain... 1507 to be precise. Look up the battle on Wikipedia if you want spoilers.
The rest is up to you now. Look at the screenshots, watch the trailer, watch it twice and watch it thrice. See if you can spot any little scraps of detail that we've missed.