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He was no doubt keen to show his boy around the picturesque city – the birthplace of Wolfgang Amadeus Mozart.
Earlier in the week, Arnie had told attendees at a renewable energy conference that the composer's music was the one thing he really misses from his fatherland, along with wiener schnitzel.
He spoke at the Vienna meeting for half an hour in both English and German.
While the actor was reconnecting with his native country, his estranged wife Maria Shriver was busy getting on with her life back in America.
She raised a smile for photographers who snapped her leaving a hair salon in Beverly Hills.
The 55-year-old is yet to file for divorce but is said to be receiving child support payments from her husband.
Arnold is also paying the private school bills for sons Patrick and Christopher reports RadarOnline.
"Maria wants to get a fair divorce settlement and move on with her life," a source told the publication.
"She has already begun to do so. She and Arnold talk quite often, it would surprise people how gracious Maria is being about the entire situation.
"Maria doesn't want the kids to suffer."
It's a little princess!