I am trying to purchase underground tickets to the coliseum in early September, and I can't get any. Anyone know when those tickets will be available?

Whenever the Italians decided to make them available, if they do. Just keep checking every day on coopculture.it. It's about all you can do.

I just walked through the ticket purchase up to giving the credit card on this site and was successful for Sept 4.

http://www.tickitaly.com/tours/colos...level-tour.php

Tickitaly is a reseller, not the official site so yes, they can take your money, but they will just hold it until they can make the purchase when the tickets become available. They also mark up the price. The price on the official website CoopCulture is 22.50€. On Tickitaly it's 28.50€.

Oh...rats, thought I found a loophole for him...sorry.

I was also looking at the www.coopculture.it and they have not posted the September days. So I also looked at tickitaly, but I wondered if the lack of September schedule at the coopculture was due to coopculture slow in updating their web site or that tickitaly took the money irrespective of if the tours would be offered or not.

They must be tweaking the website as hours change slightly for the Colosseum Sept. 1 and perhaps they also cut back the number of tours. It's not just the underground tour that isn't available, it's all tours/tickets including entry only tickets. I would just keep checking every few days and often the Italian version will be updated first.

Having taking a tour, here is what happened in September. I ended up making a phone call due to the web site non-functionality, paid by CC while on phone, gave my email address and got a reservation code by email.

1. We walked by the long line of people who did not make reservation and went straight to the reserved ticket pickup window. I got two things, a combo entry ticket to Colosseum/Palatine Hill/Forum (the same one anyone can buy) and a sticker showing the time and the type of the tour. The window told us to walk all the way to the meeting area next to elevator. It was indeed the last of the meeting area.

2. You will not even see the word "underground". The tour in English is "Guided Tour Third Floor and Hypogeum" and in Italian, "Vista Guidata Terzo Ordine e Ipogei".

3. The tour took us to a locked area on the ground floor - a small section of the area covered by the platform you cannot get to unless you are on a tour.
The underground area where the gladiators came in, area where animals were hoisted to the area, and the spring to feed the spectators. The underground tour does not include the area below the arena.
And a small section of the third level, also not accessible without being on a tour with a commanding view of the Colosseum interior and the Palatine Hill.

Moving between all these levels was done on stairs.