Been there specifically few years ago, alone, after climbing Mont Damavand I had some extra days without prior planning, ended up visiting Isfahan and Yazd with

Been there specifically few years ago, alone, after climbing Mont Damavand I had some extra days without prior planning, ended up visiting Isfahan and Yazd with some sunset on nearby sand dunes. Extremely friendly people, all spoke at least basic english, even signs were dual (farsi/english). You can't get much more safe in middle east these days. Yazd is most important place for zoroastrianism, probably first major monotheistic religion (they have fire burning there for few millenia, and some now-unused towers of silence for scavengers 'burial'). Overall, fascinating place to visit, untouched by mass tourism. Wandering randomly through central maze of mud brick streets, brings some good memories. Just brace yourself for some serious heat during summer, albeit air is very dry which helps (unlike south Iran which is supposedly brutal due to humidity). The only annoying thing - you probably won't get US visa easily with same passport (with another one for same person there is no issue)