Fascinating 2 part series on discovery civillisation (repeated saturday 28 from 4pm - 6pm).
Investigating the various secret underground factory sites and V2 production/launch facilities in part 1 and then concentrating on the last stand bunkers and shelters under the citys and deep under ground in the mountains of germany in part 2.
I've always been enthralled by such things, and no less so in this case because of the knkowlege of how and why they were created. Call it a 'subterranian wonderment' if you will
If you have the time, watch it and step back in time 60 years, thankfull that there are only empty, dripping tunnels and rusting V2 combustion chambers for company. For the most part anyway. Perhaps I'll get to see some of them for myself one day?