I am in the early stages of preparing for a possible trip to Iran in 2019. I am an independent traveler whose original motivation is an interest in the architecture of the country's mosques (and a European Union passport holder.)
Normally, I would start by reading in the Rough Guides series of guide books, but for perhaps well-understood reasons they apparently do not have a current guide book on Iran.
What are other good sources for independent travelers interested in visiting Iran (politics left aside) in terms of up-to-date (or everlasting) guide books or other printed information?