Anyone know how to make reservations to get to the underground part here? I believe this is a separate ticket.
To go to the arena of the Colosseum , you must buy a ticket with a guide for the Colosseum.
I bought tickets at this website:
and everything went perfect, remember you do not need to queue waiting with this purchase.
Enter this web site, look, there are also others:
The best tip i ever received was to buy my ticket for the coliseum at the forum....
I'm copying text from a website that i found super helpful and have passed in to all of my friends.
"The ticket kiosk at the Colosseum has by far the longest queues.
If you want to visit the Colosseum, Roman Forum and Palatine Hill do yourself a favour, buy your tickets at the Palatine Hill entrance.
Then walk uphill exploring the Palatine Hill is more gradual than from the Roman Forum and has more shade If you are visit in the hot months of summer. After performing a circuit of the Palatine Hill you will get a great birds eye view down onto the Roman Forum as you descend into it, getting a good initial orientation in the process.
The ticket gate for the Palatine Hill often has no queues at all and is midway down the road Via di San Gregorio that runs from the Colosseumalong the base of the Palatine Hill. The ticket gate is less than 5 minutes walk from the Colosseum."
since being told this tip I've only ever bought my tickets at the forum, strolling right into the colosseum and side stepping the 30 minute or longer wait!
Mentioned in this answer:
Check out this website for ticket info: http://www.coopculture.it/en/colosseo-e-shop.cfm