On one of my days off, I decided to take my "resident" cap off and do Chicago's most touristy things possible. I hopped on a trolley, waited in lines with the throngs at Garrett Popcorn and did that thing at the "Bean" where you stand back and pretend to squeeze it between your fingers. Mostly, I did it to reconnect with my adopted hometown and to be amazed by weird and wonderful tidbits about Chicago. Did you know …

Al Capone is credited with adding date stamps on milk

Al Capone … do-good public servant? According to Craig Alton, a guide with Untouchable Tours, Chicago's most famous gangster provided milk for city schools after their milk budget was slashed. Capone had one condition: that they print expiration dates on bottles, because his family was once sickened from old milk. And according to the book "The Outfit," by Gus Russo, Capone also successfully lobbied the City Council to set guidelines for what could be sold as Grade A milk. Untouchable Tours, $30. 773-881-1195, gangstertour.com

There's a swimming pool in the underground Pedway

Well, it's not as if you can jump in clutching your briefcase. Glass windows allow pedestrians to peer at lap swimmers at the East Loop LA Fitness beneath Randolph Street. "All the women on my tour say they'd never swim in that pool!" said Chicago Pedway Tour guide Margaret Hicks. Chicago Elevated (four tours available), $15. 773-593-4873, chicagoelevated.com

Some city buildings are floating on a steel raft

Because of the soft soil beneath downtown Chicago, some older buildings were built upon a floating raft foundation, said Bill Elliott, of the Chicago Red Cap Walking Tour. A base of crisscrossed steel rails helps buoy structures, including the Auditorium, the Rookery and the Monadnock buildings. Chicago Red Cap Walking Tours, $15-$20. 312-927-0689, chicagoredcaptours.com

Mussolini gave Chicago a Roman column

Italian aviator Italo Balbo led a trans-Atlantic squadron of seaplanes from Rome to Chicago in 1933 during the Century of Progress World's Fair. As a gift of appreciation, Italian head of state Benito Mussolini donated a 2,000-year-old column set on a travertine limestone base. It's known today, said Steven Beier, of Steve's Segway Tours, as the Balbo Monument and sits near a bike trail in Burnham Park, just east of Soldier Field. Steve's Segway Tours, $65-$80. 312-946-9467, stevessegwaytours.com

Why there are Y's all over

On city bridges, on the Chicago Public Library logo, behind the middle C of the Chicago Theatre marquee — you'll find the Circle-Y symbol, the city's designated "municipal device." Walt Chadick, tour guide trainer with Chicago Trolley & Double Decker, said the Y is a representation of Wolf Point, where the North and South branches of the Chicago River come together (near the Merchandise Mart). The design grew from a Chicago Tribune contest in 1892 that sought a symbol to represent the city during the World's Columbian Exposition the following year. Chicago Trolley & Double Decker, $26 (adult, purchased online), coachusa.com/chicagotrolley

A ticket booth from the Columbian Exposition stands in Oak Park

According to Adam Ross, of the Frank Lloyd Wright Preservation Trust, an original ticket booth from the 1893 World's Columbian Exposition stands in the north yard of the Hills-DeCaro House at 313 Forest Ave. Constructed in 1883, the home underwent a redesign by Wright that was completed in 1906. Its owner, attorney Nathan G. Moore, gave the home and ticket booth to his daughter Mary as a wedding present. Frank Lloyd Wright Pedal Oak Park bike tour, $35, gowright.org

There are miles and miles of telephone cable at Willis Tower

From Susan Ross, of the Chicago Architecture Foundation: About 43,000 miles of telephone cable run through the Willis Tower (formerly, and forever to some, Sears Tower). It's enough cable to stretch across the continental United States about 15 times.Chicago Architecture Foundation boat tour, $35, 312-322-1131, caf.architecture.org

The word 'lollapalooza' was popularized in Chicago

A century ago, Michael "Hinky Dink" Kenna and "Bathhouse John" Coughlin were co-aldermen of the 1st Ward and known for throwing elaborate fundraisers that packed 15,000 revelers into the Chicago Coliseum. But according to Ken Melvoin-Berg, of Weird Chicago Tours, the infamous 1st Ward Ball — attracting its fair share of pickpockets, pimps and unsavory characters — was notorious for being where prostitutes, ahem, rendered their services. En masse. After one such gathering, Hinky Dink said of the party: "It's a lollapalooza!" Weird Chicago Tours, $30 (11 tours available), 888-446-7859, weirdchicago.com

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