The first paragraph did allude to the fact that Florence and Venice were also recreated using similar methods. Rome in 1503 should look similar in architectural style to the city of Florence featured in 'Assassin's Creed 2.' But the art director for 'Assassin's Creed: Brotherhood' decided to give Rome the Baroque architectural style of the late 16th century, so that gamers would have a new-looking virtual playground that is also more recognizable to modern eyes. 'The fact that you can go inside these buildings is incredible.' 'It's fine that you have a Colosseum that's not elliptical, because it looks like the Colosseum,' Simonetta told LiveScience. That's because the challenge of making different shadows for all sides of the building would have driven game designers nuts, Simonetta said. The famous Roman Colosseum still looms above virtual Rome, but its in-game shape is circular rather than elliptical.
The city itself was not meant to be extremely accurate as possible due to game constraints. I don't know about Florence or Venice, but because Brotherhood mostly takes place in Rome, an actual Renaissance scholar was consulted during the design of the city of Rome.