Two days in Rome turned out to be just about right. Venice was right up Dan's alley; it was fun and imaginative and filled with tiny crooked paths. Rome was huge and crowded and noisy and filled with homicidal drivers. More to the point, when you're thirteen, you have a limited capacity for ruins.
He was fascinated by the Colosseum, and we spent our entire first morning there.
After that we'd planned to go see the Roman Forum and the Palatine Hill, but by the time we'd finished lunch...