Various sightseeing companies run guided bus tours of the city center. Chicago Trolley (daily 9.30am-5pm; $20; $25 for two days, hop-on; tel 773/6485000, ) hour-long tours begin at the Sears Tower. Chicago Motor Coach ($10; tel 312/666-1000) runs double-decker buses that pick up at the Sears Tower, the Art Institute and Navy Pier. The former, though, is often ranked "best tour in Chicago" by Chicagoans.

The Chicago Architecture Foundation , in the Santa Fe Building at 224 S Michigan Ave (tel 312/922-3432, ), runs a number of highly recommended tours throughout the city. Among these are two information-packed walking tours of the Loop, giving a friendly in-depth introduction to Chicago's buildings and history ($10 for 2hr, $15 for both tours). It also offers walking tours of Frank Lloyd Wright's buildings in Oak Park, Historic Pullman and other neighborhoods; bus tours of the Loop and Near North ($15; 2hr), Hyde Park and Frank Lloyd Wright's Robie House ($25; 3hr 30min). Perhaps the most popular of all are the excellent ninety-minute Chicago Architecture by Boat tours, which leave from Michigan Avenue and Lower Wacker Drive (May-Oct Mon-Sat 3 departures, Sun 2 trips; $21). Other sightseeing boat tours include those offered along the river by Mercury (tel 312/332-1368, ; $14) and Wendella (tel 312/337-1446) during the summer season; and Spirit of Chicago Harbor Cruises ($17; tel 312/836-7888), who continue year-round, sailing from Navy Pier. Shoreline Sightseeing Tours ($17 for architectural cruises, $10 for lake cruises; tel 312/222-9328, ) is another good option, with architectural river cruises as well as lake tours, a slightly different look at the architecture of Chicago.