Hi, does anyone know if the lower levels of the Colosseum have reopened?

I'm interested in this as well.

Me too.

They haven't reopened yet, but they probably will sometime this month. Keep an eye on this site to buy tickets for the underground and third-tier tour (you have to choose Collect onsite):
http://www.ticketclic.it/gb/html/musei/colosseo.cfm

bookmarking

They have opened but buying tickets online (I thought) was very confusing. I found these instructions on slow talk.com and it worked perfectly.
Here's what I did in this order:

Go to Pierreci home page/English http://www.ticketclic.it/Gb/HTML/musei/colosseo.cfm
Buy Ticket
Book Ticket
Colosseo
Agree
Now you'll be at the Omniticket site
Collect on Site/Buy Ticket (right side of page)
Put in your date (it will not show Visita Sotteranei at this point)
Confirm
Next you'll be given the various tour options and you'll see Visita Singoli Sotterranei; choose your tour and time and continue to checkout.

Good luck!

I went here http://www.tickitaly.com/tours/colos...night-tour.php and bought the tickets with just two clicks. Pick a date and pick a time. You're done. Very easy. Going next week.

Tickitaly is a reseller so their prices will be higher although they don't mark up as much as some other resellers. Michele's link is for a night tour.

kat4kat's link is the official booking link (Pierreci/ticketclic).

I see tickitaly has increased their prices from last year and are charging 37.50€ for the tour. With Pierreci it is 21.50€

Pierreci/ticketclic:
Colosseo + Palatino + Foro Romano
UNDERGROUND TOUR  ENG
Thursday, 14 June 2012
Time : 09:41 INTERO - ADULT - VISITA SOTTERRANEI €21.50 1 € 21.50 Total € 21.5

Tickititaly:
June Colosseum upper and lower levels tour
Guaranteed availability for the Colosseum upper and lower levels tour
Selected options:
Date of tour: Tuesday 19th Jun 2012, 11.00AM
€ 37.50 x = €37.50
Subtotal: €37.50
Total: €37.50

kybourbon,
Wow their prices have gone up. In January I paid 110 euro for four people so 27.50 euro each through the tickitaly site.

Recheck that, I just looked at the website and it says 27.50 Euro, not 37.50.

It appears Tickitaly has two different tours. One is 90 minutes for 27.50€ (doesn't include Forum) and the other is 3 hours for 37.50€(includes Forum).

The Pierreci underground tour seems to be 90 minutes (21.50€) for the underground tour only where as the Tickitaly appears to be 90 minutes for Colosseum, upper level and underground combined.

http://www.pierreci.it/home-page/en/...-hypogeum.aspx

Pierreci offers a 45 minute tour of the Colosseum for 5€. It doesn't have a guided tour for the Forum, only audio guides (5€).

http://www.pierreci.it/home-page/en/.../colosseo.aspx

http://www.pierreci.it/home-page/en/...ro-romano.aspx

My package includes the Colosseum Upper and Lower Guided Tour. It also includes the Forum and Palatine Hill but not guided for these. Just double checked my ticket.

General admission tickets include the Colosseum, Forum and Palantine. The entrance ticket should also be good for two days. With outside tour companies, you are booking an entrance ticket + a tour.
From Pierreci:
COLOSSEO/FORO ROMANO and PALATINO valid 2 days:
ADULTS € 12,00

Okay I think I must have the Pierreci underground tour ticket for 90 minutes since I paid 21.50€. My question is how much time should I leave to tour the Colosseum, Palatine Hill and Forum?

We went to Rome last year and spent one full day visiting the Colosseum (with underground tour), Palatine Hill and the Roman Forum. There was a lot to see and it was a super hot day so be sure to wear comfy shoes and bring water. All these sights are close to each other. It was an amazing experience - enjoy!