Recently on a bus trip from Rasht, Iran, to Tehran, Iran, the driver's assistant came down the bus aisle, ordering all the curtains closed on one side, and for a few minutes we were actually forbidden from looking out the windows on that side!
I can only assume he didn't want a hassle with military or something with people seeing ... 'something'? It was a local bus, mostly (we were the only foreigners as far as I know), and was a regularly scheduled normal bus.
We'd just passed Sefid Rud Lake, and heading south, it was on the right side of the bus. As best I can tell, we were on or close to this section of road in google maps (I took a GPS reading a short time later).
I'm wondering what was on that section of the road that we weren't allowed to see? I asked my Iranian friends, but they didn't know either. Just a military base or something else?