Towers electrically insulated against ground with closed rooms may exist only a few in the world. Here are the examples I know:
1.) Berlin Radio Tower, perhaps world's only observation tower standing on insulators, however grounded over the elevator shaft, which has beside an observation deck also a tower restaurant (
http://en.wikipedia.org/wiki/Funkturm_Berlin )
2.) Blosenbergturm, the free-standing mast radiator of famous Beromünster transmitter. It contains 150 metres above ground a cabin with a coil, which is used for feeding its pinnacle with high frequency power (
http://en.wikipedia.org/wiki/Blosenbergturm )
3.) Masts of Droitwich Longwave Transmitter (
http://tx.mb21.co.uk/gallery/droitwich/droitwich-ab.php ,
http://en.wikipedia.org/wiki/Droitwi...itting_station ) with cabinets over the basement
Do you know further towers insulated against ground with closed rooms?