In the summer of 1989, Van Morrison was travelling in Greece with a film crew, making the documentary One Irish Rover. One sunny day, he was joined in Athens by Bob Dylan, who'd just ended a European tour. They brought their acoustic guitars to the place in Athens where the ancients believed the Muses lived: Philopappos Hill, traditionally known as the Hill of Muses.
With the Acropolis in the background, Morrison sings two of his songs: "Foreign Window" and "One Irish Rover"; Dylan accompanies him with harmonica, guitar and vocals. In the second clip below, they do a version of Morrison's "Crazy Love".
"Foreign Window" and "One Irish Rover"
"Crazy Love" (includes the credits for the film One Irish Rover)
There's also a version of "And It Stoned Me", but the audio and video quality is poor.