Do you already have tickets? You need to pre-book the tickets online if you do not have them! There is going to be a lot of people and I can make you skip the line…
If you should ever go to Rome remember what I have just written because there will be a lot of people that will give you this crap. I can promise that there is no pre-booking needed, there are no lines that those people can help you skip.
Especially these days, there was not even a line at the ticket counter… I cannot really say, but I guess if there were many more people in Rome, I have the feeling that even then are not lines to skip – and even then you do not need to have a pre-booked ticket.
There is s saying in Switzerland: “Wenn die Sonne lacht, Blende acht.» means «if the sun is smiling, use F-Stop eight».
Those settings will get you the most details in bright light. The Auto-Mode with the camera is not choosing the same settings that will make the colors look “wrong”.