I went to the www.ticketeria.it website to order tickets to the Borghese Museum and ran into two puzzles. (1) In purchasing tickets, it asked/required a "fiscal code." What is that? It has an asterisk next to it, so it is deemed necessary for some reason. (2) Though I want to visit and sign up for certain hours (9 am) to walk around, it tells me I have "seats". Is that just a part of signing up for theatre performances and they haven't found a way to eliminate it from museum sites.
Have you tried the official Borghese site: http://www.galleriaborghese.it/borghese/en/edefault.htm That is who I used and had no problems with their booking site (TicketOne).
Don't worry about the seat assignment it is just a space as they only let a certain number of people in at the appointed intervals.
If you click through to pay for the ticket, after selecting your country the Codice Fiscale field is not mandatory unless Italy is the country your credit card is tied.
Many thanks to you both! Tickets successfully bought! I also learned that "tosc" in the url stands for TicketOne sistemi culturali--I had worried that I was confusing websites, but I was not. Grazie mille!