Does anyone have info about touring underground Rome or under the Vatican?
The Scavi tour under the Vatican is really interesting. You have to book in advance via e-mail... The information is on the Vatican website (vatican.va). Once you select English, scroll down to 'Visits to the Vatican Necropolis' and click on 'Excavations office'. If booking well in advance, don't be worried if you don't hear back right away. I sent an e-mail last April for September and didn't hear back from them until the end of June. I've also had friends who have booked 2 weeks before their trip and received a response immediately.
I took the Scavi Tour last winter, and it was worth every Euro I paid! I booked two months in advance, and has some trouble at first. My cox.net e-mail account would not allow me to send mail to the address to request tickets. After several times of trying, I tried with an AOL account and had no problem.
You can view the ruins below the church of San Clemente without an appointment.