Thanks for the comments, guys. I just can't stop thinking about Rome. I wish we'd stayed longer! It's an amazing place because it's the real thing, the original. The great buildings of London, Washington etc are just imitations of what the Romans built two millenia ago. And the Pantheon is without comparison. The weird thing is that the upper half-sphere was made by the Romans using concrete! Thanks again, your interest is appreciated.
Tadao Ando, the famous Japanese architect recently disappeared, was used to say that he learnt what was architecture looking at the Pantheon.
This photo could be considered an explanation of that statement ;-))