I believe, there is an informal treaty not to built structures of any kind taller than 365.25 metres (= 1200 ft) in Europe (excpt former Soviet Union).
It should be noted, that only 5 antenna structures were built in Europe except of former Soviet Union, that overpasses this mark.
These are/were:
* Konstantynow Radio Mast, Konstantynow, Poland, built 1972-1974, collapsed in 1991, height: 646.4 metres (
http://en.structurae.de/structures/d...fm?id=s0000672 )
* Hellissandur longwave transmission mast, Hellissandur, Iceland, built 1963, height: 412 metres (
http://en.structurae.de/structures/d...fm?ID=s0014958 )
* Old TV Mast Emley Moore, Emley Moore, UK, built 1964, collapsed in 1969, height: 385 metres (
http://en.structurae.de/structures/d...fm?id=s0013859 )
* Belmont TV Mast, Donington on Bain, UK, built 1965, height: 385 metres (
http://en.structurae.de/structures/d...fm?ID=s0014952 )
* Gerbrandy Tower, Ijsselstein, Netherlands, built 1961, height: 375 metres (
http://en.structurae.de/structures/d...fm?ID=s0012623 )
* TV Tower Berlin, Berlin, Germany, built 1969, height: 368 metres (
http://en.structurae.de/structures/d...fm?ID=s0000113 ). The height of TV Tower Berlin was until the renovation of its antenna mast in 1997, 365 metres, so it did not exceed the 365.25 metres at time of completion.
When you go to lower height values, you will find out that the number o structures in the corresponding height ranges grow fastly and that nearly each European country has at least one structure in the height range between 300 and 365.25 metres in form of a guyed mast, a free-standing tower, a chimney or in case of France also as a bridge.
This list shows clearly that after 1965 except of Konstantynow Radio Mast no structure taller than 365.25 metres was built in Europe outside the area of former Soviet Union, although there are and were many proposals for structures taller than 365.25 metre as that for a 750 metre tall TV tower or for skyscrapers in Paris.
Even at present time there is no such structure under construction in Europe outside the GUS-states!
From all proposls only the proposed rebuilt of Konstantynow Radio Mast was close before realizatio ( some basements work were made, before it was cancelled after protests of people living nearby fearing electrosmog).
Messina Strait Bridge, which was until short time ago the best candidate for Europe's next structure exceeding the 365 metre mark, was obviously also cancelled for next time ( although the idea of a bridge over Messina Strait will never die and if it will be ever built, it will be built for practical-technical reasons as suspension bridge with supertall bridge pillars. A tunnel would be not a good choice, because Mssina Strait is very deep)
I believe, that the next structure in Europe exceeding the 365.25 metre mark will be Torre Solar in Spain. But until no construction work definitely started for it, one should not elive, that it will be built ( in my opinion this tower should be built higher than the proposed 750 metres, not only for prestige, also to mke the power station it should serve for more efficient)
For supertall skyscrapers in Europe (except former Soviet Union), I believe there is only a bare chance of realization. First, living in high-rise buildings is not popular in Europe and the richer people prefer living in houses with gardens.
Then many companies reduce their administrative section, so the requirements for office space decrease. For example the chemical company Bayer in Leverkusen replaced its old headquater in a highrise building (
http://www.leverkusen.com/guide/Arch.../Lev00054.html ) by a new headquater in a flat building (
http://www.leverkusen.com/guide/Arch.../Lev00294.html ) and not by a taller highrise building!
The highrise building "Langer Oscar" in Hagen (
http://en.structurae.de/structures/d...fm?ID=s0015519 ) was replaced by the lowrise "SparkassenKarree" (
http://www.velta.de/de/pdm0502/projekt.htm ).