Would like to recommend visiting Iran to all those interested in culture and history. We, a couple in our 40s, visited Iran in March. We enjoyed every minute of the holiday. The country is really rich in culture and history. There was a world-class site to visit on every day of the tour. The infrastructure is excellent. Roads, hotels and vehicles were in excellent standards. The food is amazing and hygiene is well maintained. People are friendly and we didn't notice any security issues.
We visited Tehran, Kashan, Isfahan, Yazd and Isfahan in 10 days. This took us back into 7000 years of history full of art and culture.
This holiday was operated by IranianTours (http://www.iraniantours.com) which I can highly recommend.