Lou Mitchell's legendary restaurant and bakery first opened for business in 1923 and has been a Chicago institution ever since, serving breakfasts, lunches and "the world's finest coffee" to presidents, celebrities, ordinary Chicagoans and visitors from all over the world. It was also one of the first places to eat on the original Route 66 and retains much of its 1940s/50s interior including the booths, counters and stools.
If you go:
Every child and female diner visiting Lou's is presented with a box of Milk Duds, a traditional that goes back decades. The popularity of the place means you should either arrive early or be prepared to wait in line. Opening hours are Mon-Sat 5.30 am-3.00 pm; Sun 7.00 am-3.00 pm.
Links:

565 W Jackson Blvd
Chicago, Illinois 60661-5701 USA
Phone Numbers:
Information
+1 (312) 939-3111
+1 (312) 939-3111