Virtually every major architect in the past 125 years has worked in Chicago.  Some of the most famous American architects, including Daniel Burnham, Louis Sullivan, Frank Lloyd Wright and Mies van der Rohe have called Chicago home.  But Chicago is not just home to dead architects.  Chicago-based Helmut Jahn of Murphy/Jahn, and Lucien Lagrange, among others, are changing the face (or at least the profile) of Chicago every day.  World famous architects are creating new structures in Chicago. Among them are Ricardo Legorreta who designed a new dormitory at the University of Chicago, Frank Gehry who designed a bandstand and pedestrian bridge for Millenium Park and Santiago Calatrava who has been chosen to design the 115-story Fordham Spire, which will be the tallest building in the U.S., if completed.  The photo below shows Mies' IBM building, the Hancock Building, Wrigley Buyilding and Tribune Tower, among others.  In the foreground is the new Trump Tower  under construction.

 Chicago is proud of its world class collection of architecture, and rightfully so. From the first skycrapers in the world as exemplified by the Burnham on state street (now turned into an interesting boutique hotel - see photo below)

to the Hancock and Sears towers, to the stunning new buildings along the river, there is something to be seen on every corner. For the tourist who doesn't know where to begin help can be found at the Chicago Architecture Foundation, located at 224 South Michigan Avenue. They run a wide variety of tours, including walking tours of the loop. Especially popular is their River Cruise, reservations available at their headquarters are highly recommended since the river cruise fills up fast.  Their walking tours are great.  For an out of town visitor, I would recommend either the Modern or Historic Skyscraper tour (or both!)  The historic tour is at 10am everyday.  The modern tour is at 1pm daily.  I think you can get a discount if you do both tours back to back.  An out-of-town family membership with the CAF costs $60 as of August 2008, and will get you discounts on some tours (such as 2-for-1 on the river cruise) and other tours are completely free (including 5:30 "Happy Hour" tours that end with a beer or wine at a local bar.)
     
A bit further afield is Oak Park, with its collection of Frank Lloyd Wright buildings. Easily accessible from the CTA Green line, a good first stop is the Frank Lloyd Wright Home and Studio.  Oak Park is home to more Wright residences than any other city.  

In addition to Oak Park, consider visiting Chicago's Hyde Park neighborhood, home to Robie House considered to be among Wright's greatest works, and the city of Evanston, where Daniel Burnham lived and which has an eclectic collection of Victorian homes.

The bungalows of Chicago, mostly built  between 1910 and 1940, are the essence of real Chicago architecture.  These solid Arts & Crafts style brick buildings were where ordinary people lived stylishly.   Find out more about where to view Chicago's "bungalow belt" at the Chicago Bungalow Association.

 The Chicago department of Cultural Affairs also offers visitors a chance to spend time with a local resident FOR FREE!

The Chicago Greeter program offers visitors (groups of up to 6) a chance to hook up with a local for a FREE tour of over 25 neighborhoods, architectural attractions, hidden gems, or whatever special requests the visitor might have.  The program even includes a FREE VISITORS PASS for use on the CTA's "EL" or Bus system!  The program also offers an INSTAGREETER© option; this option allows visitors who didn't have time to make a reservation to meet up with a Chicago Greeter representative at the Chicago Cultural Center and spend an hour with them walking around the loop!  It is a fantastic way for visitors and locals alike to discover the hidden gems of Chicago!  A must for architect lovers and architecture students.