Marcel Miquel wrote:
"(...)After reading this site and other informations, I think that  
Sant'Offizio was an extraterritorial zone contiguous to the vatican  
state since the Lateran treaty of 1929, so when  the Papal Hall was  
built in 1972, it was built part into Vatican territorial land and 
part into extraterritorial land, so there was no land tranfer: simply 
it's a building divided by the border, as you can see on another map 
in the same site:
http://www.globalgeografia.com/europa/curiosita/aula_paolo_vi.gif
(...)"
I wonder whether that border is marked in any way inside the building.
Anyway, I think you're right, that there was no land transfered. That 
the Sant'Offizio area is extraterritorial _and_ adjacent does show 
very clearly the difference between extraterritorial and sovereign 
Vatican territory.
A list of the extraterritorial areas can be found at 
http://www.vatican.va/news_services/press/documentazione/documents/sp_
ss_scv/informazione_generale/extraterritoriale_it.html . I don't 
think there is made a difference between type 1 (no expropriation and 
no taxes) and type 2 (no taxes) areas is made here.
Peter S.