According to this map from the Nuclear Threat Initiative (2006), your GPS reading at the western bend of the road between Rasht and Qazvin corresponds almost perfectly to “Mo-Allem Kalayeh: Suspected nuclear research center“.
However! This (ancient) page gives the site’s coordinates as 36°26’05″N 50°29’53″E, which is a) a lot closer to where Wikipedia thinks Moallem Kalayeh (معلم كلايه) is located, and b) nowhere near where you went. That said, the FAS site seems to be simply matching names to towns, so it’s by no means clear which of the two is wrong…
Credit:stackoverflow.com‘