No idea about the set, but I strongly suspect you are right, Steve, more than likely making use of those existing facilities, which would make sense since they have them already built. Location filming on the actually sites would probably be a bit tricky, not just because of the historical significance but because sections are a bit worse for wear these days and crumbling away since being exposed to the air once more.

Doctor Who nerd: In addition, The Two Doctors was filmed in Spain, Planet of Fire was filmed in Lanzarote, and there was some location filming in New York (not involving the principal cast) for Daleks in Manhattan/Evolution of the Daleks.

Annoying pedantic nerd: strictly speaking, it was Vesuvius that erupted, not Pompeii.

Are the Who team doing a Carry On Cleo and filming on someone else’s sets? Apart from the Doctor and Donna, the BBC’s photo looked awfully like HBO’s Rome, which was also filmed at Cinecitta.

Last year’s “Daleks in Manhattan” featured some second unit work filmed in New York (although the principal cast never left Cardiff).