The Withnail & I star told The Guardian that he is a big fan of Smith.
McGann said: "I admire artists who are ageing and still retaining their edge. Like Patti Smith - I saw her play live a few weeks ago and was moved to tears."
He added that if he could own a single piece of art, it would be Lorenzo Lotto's Portrait of a Gentleman in his Study.
"I'd stand in front of it, imagining it's me in the painting," he said.