1) This is an experimental plane called the X-33. It is the future of commercial flight, with the capability to travel from New York to Switzerland in an hour! Robert flies in this plane twice in the book, once from from New York to Switzerland and from Switzerland to Italy.
2) Ambigrams are found throughout Angels & Demons, and are used by the Illuminati to brand Vittoria's dad and the 4 cardinals. There is a total of 5 ambigrams and they are:
3) The Vatican City is, in my opinion, the biggest part of the setting because its where the climax and also most of the action occur. There is lots of subtle facts about the Vatican City throughout Angels & Demons. For example Robert and Vittoria get the pleasure of going inside the Vatican's Archives. Some documents are thousands of years old in there!
4) The Secret Vatican Archives are a restricted section inside the Vatican where important documents owned by the Vatican are stored. There is an estimated 84 km of shelving, with around 35,000 volumes in the catalogue alone. The oldest surviving document in the archives dates back to the 8th century; according to the official Vatican website.
