Romania or Bulgaria, or even Russia. They may still have the old listening infrastructure in place, although I hear that Stasi headquarters in the former DDR is now an acupuncture clinic.

The Stasi listening infrastructure wasn't solely in their headquarters. Listening stations for terrestrial frequencies were spread along the borders, notably here is the station on the Brocken, a mountain in the Harz. The central station for interception of satellite traffic (read: international telephone communication, even when not entering or leaving the country) was located in Biesenthal, a small town near Berlin. It's hard to reconstruct what part of interception took place in the Stasi HQ, my guess is that all international telephone traffic leaving or entering the country was intercepted there. For technical reasons it was impossible to intercept all domestic traffic from a single central location, the telephone system worked on a purely mechanical basis. It seems that almost all of the telephone surveillance equipment was destroyed during the revolution or shortly after. Things look different for the mentioned radio equipment. The Stasi used a combination of Russian and self-made technology. The top-of-the-notch Russian equipment is back in Russia. But most of the Russian equipment was sold by the Russian guards (their pay is _really_ low, even more so when compared to western money), the Stasi equipment was forgotten about and eventually stolen. This equipment is now mainly in the hands of about 3 or 4 individuals.