Dear Douglas,
Thank your for your question. There are two options:
-Shared walking tour 25€ per person + ticket entrance (it depend on the day, not available always, min 10 people. If there are not 10 people, in many cases we cancel the tour).
-3h private walking tour 170€ + ticket entrances. You pay for the private tour guide, it doesn't matter if you are 1 or maybe 6 or 10 people. We recommend not more than 15 people. Is just a private walking tour for you (your family, party, etc). Not shared. In fact we can offer 3h walking tour or my favorite for 2017: 4h Roman Walking Tour.
If you have more questions or you need more information, you can send us an e-mail or check our website with pictures, videos, info, etc. We have many booking for 2017, so try to contact us and book the tour before Christmas.
On the other hand, many thanks to all tripadvisor users for your answers, we really appreciate having trusted in our private services and also help us. MANY THANKS!