Steelbird just reminded me: I completely forgotten about the two military training I had in high school and in university.
The training in high school was conducted in a HQ-2 (SA-2 copy) SAM Battalion about 100km away from my hometown. I stayed in the base for three weeks and spent most my spare time watching the missile site. We were allowed to see inside the command & control centre of the battalion inside several truck-mounted shelters. The unit did a demonstration of loading a HQ-2 from the tranportaion truck into the fixed launcher. The officer of the unit told us that it should take only no more than five minutes under the training standard, but the the actual process took about 15 minutes .
My training in my university was conducted in a Chemical Defence Regiment near Beijing. They did not have any equipment for me to watch apart from few old trucks. However, one day we were allowed to visit an underground nuclear-protection shelter nearby. The unit officer told us that the shelter would be used by the government and party officials during a nuclear war. The part opened to us was only a small part. In fact, a whole mountain was emptied to build these facilities. The part we visited looks pretty like a hotel with corridors and empty rooms. I remember the room number was something like 501, 502, 503, suggesting that there were at least five stories in the facility.