If I have a 45 minute tour booked, do I have to leave the Colosseum at the end of that time?
Not that I've ever heard of. The only restrictions are the areas you're not allowed to be in without a tour/guide (underground, upper tiers or arena floor) and being out by closing time.
No you don’t have to leave. We stayed for 2 hours after our tour.
thankyou very much - it helps a lot to determine what type of tour to book