On Federal Plaza (East of the Post Office)
Adams & Dearborn (230 S. - 50 W.)
Tuesdays, Mid May until mid October, ca. 7 a.m. - 3 p.m.
Prudential Building Plaza
Lake & Beaubien Court (200 N. - 150 E.)
Tuesdays, June through October, 7 a.m. - 3 p.m.
311 S. Wacker (311 S. - 350 W.), On the Park at Jackson & Wacker
Thursdays, June through October, ca. 7 a.m. - 3 p.m.
Washington & Dearborn (100 N. - 50 W.)
Thursdays, Mid May until end of September, ca. 7 a.m. - 3 p.m.
All dates and times are subject to change and shall give you with a rough idea. Check with local newspapers when arriving in Chicago.