Maranjab Desert is the classic sand-and-salt landscape reached from Kashan: dunes, hard desert tracks, a Safavid caravanserai, and the pale edge of the salt lake beyond. It is not an urban sight you can squeeze between house museums; it works best as a half-day or full-day trip with a driver who knows the tracks.
The appeal is strongest late in the day, when the dunes take on colour and the heat drops. The area is fragile, so avoid treating it as an off-road playground. Go for the big empty views, the old caravan route atmosphere, and the sudden reminder that Kashan sits right on the margin between oasis town and central Iranian desert.