Just behind the city of Yazd there are towers of silence - where they chopped their dead and left them to vultures - still used in '70s. I guess their cultural revolution stopped these practices, so now they just bury their dead in big concrete slab (not spoiling the elements like earth, water or air) behind the city.
Truly remarkable places to visit, before mass tourism will come (or US bombs the place for some obscure reason completely unrelated to oil and local power games). Cannot recommend enough! Just bear in mind you won't be able to go to US afterwards but... as non-US, I would always choose such a wonderful and welcoming country and great people over police state of US these days (as much as I like regular US folks, the system you guys live in leaves much to be desired)