Van Morrison and Bob Dylan performing "Crazy Love" with Acropolis in the background, for a BBC documentary.
"BBC2 filmed a career overview entitled One Irish Rover in 1991, which opened with Van Morrison and Bob Dylan singing a duet on the Hill of the Muses above Athens, Greece. Dylan and Morrison performed duets on "Crazy Love" "Foreign Window" and "One Irish Rover". The Independent described "the Irish singer flanked by Bob Dylan and the Acropolis: all three of them legendary, all looking their age, and all a waste of time talking to with a microphone in your hand."
(Information source HERE)
I warmly thank Aleksandar, an archaeologist from Belgrade, who kindly brought this to my attention.