Professor Davis found addition information about the Sofia transmission facilities from this website:   http://www.predavatel.com

TV tower Kopitoto in Sofia, Bulgaria:

Designers: arch. Lyuben Popdonev, arch. Stefan Tilev, dipl.eng. Ivan Yantahtov
Geographic coordinates: 23°29'E 42°45'N, Altitude: 1345m, Antenna height: 108m

Old TV tower in Sofia, Bulgaria:

On Aleya Yavorov in Borisova gradina park,  built in 1959.
Geographic coordinates: 23e2031/42n4036; Altitude: 595m.; Antenna height: 180m.

The website gives a lot of detail about the transmission frequencies, powers, etc, of radio stations in Bulgaria (but I did not see anything about TV frequencies, etc.), and has an English language and Bulgarian language version - unfortunately the English language version seems somewhat incomplete - and on my computer, I could only see the photos in the Bulgarian version.  The site also gives links for listening to many Bulgarian radio stations using Real Player, etc.


Information about structures around the world:

Try this link:    http://www.structurae.de

It is a huge database of buildings, etc. with some photos, and there is a big collection of Communications Towers:
http://en.structurae.de/structures/ftype/index.cfm?ID=2013

The emphasis is on the mechanical and civil engineering aspects, rather than the radio engineering.  However, searching the site can be rather slow, in my experience.

Thanks to Professor Anthony C Davies for these photographs.