Banksy's sketch is believed to be a nod toward a famous scene from "The Untouchables."
You could say he blew in and out of the Windy City, but he definitely left his mark.
Bansky, an eccentric British street artist whose unknown identity has been fodder for that country's notorious tabloids, is believed to have posted one of his stenciled pieces at the corner of Randolph and Peoria, on the side of an Veerasway restaurant.
It appears the artist, whose prints typically sell for thousands of dollars, left his handiwork sometime last week.
The picture first appeared on Banksy's Web site -- which is usually how word about these things gets out -- and Oliver Hild, owner of Maxwell Colette Gallery, set off to find it, with the image of the Willis Tower in the background his only point of reference.
"Other people in the neighborhood had noticed it and thought it was just a funny street piece," Hild said. "If you look at the space he picked, there's no direct light. It's very dark at night, so he could have been in and out very quickly."
Hild says the Chicago sketch is "classic Banksy and a visual nod to the movie 'The Untouchables,'" specifically the scene where the baby carriage falls down the stairs in Union Station.
Although Banksy holds on to his street cred by often selling his original works at well below market value, his Chicago visit was likely aimed at promoting his new movie, "Exit Through the Gift Shop," which premiered in Chicago April 30. Banksy appears in the film with a hooded cloak, darkened face and his voice distorted.
The artist appears to have headed north after his Chicago visit. Three of his stencils turned up on Toronto's streets over the weekend.
His previous sketches have appeared on walls around post-Katrina New Orleans and the Palestinian segregation wall in the West Bank.
As for the Chicago piece? Peep it now before it's gone.