"I knew I was going to be coming to Chicago and the one thing that I wanted to do was the river cruise," said Kristen Moore, 35, of Phoenix, snapping photos on the tour, sponsored by the nonprofit Chicago Architecture Foundation.
"There's so much history in the buildings here."
The city's rise in the world of architecture began after the Great Chicago Fire of 1871 destroyed swaths of buildings, and the late 19th century saw the city's architects become world leaders -- designing everything from the employee-packed skyscrapers to quaint homes that now make up the so-called Bungalow Belt.
Isolated from the East Coast's European influences, Chicago's historic architects were known for putting aside common ideas about design, creating a unique and different way of building.
So innovative were their ideas that Chicago is considered the home of the modern skyscraper. Among the most famous are the 110-story Sears Tower -- the tallest building in the U.S. -- and the Hancock Tower, along Lake Michigan.
"We have always thought big," says Charles Stanford, a docent and architecture expert with the Architecture Foundation. "Chicago was always bold about the way we built. We sort of really do believe that the sky is the limit. That if engineering will take us there, we'll go."
The Foundation tries to put modern marvels and the city's classic buildings in context for visitors. The group hosts a museum on Michigan Avenue and offers more than 80 different boat, bicycle, bus and walking tours.
Moore said she hoped to catch glimpses of the neoclassical and French classical building styles she loves. Tribune Tower, built in 1925, and the under-construction Trump Tower, were on her list.
There soon will be more to see, with three more skyscrapers under construction.
The Chicago Spire, designed by renowned architect Santiago Calatrava, will twist skyward for 150 stories and become the tallest building in North America. The Trump Tower will be 92 stories and Waterview Tower 90 stories.
Interest in Chicago architects increased after the 2004 publication of Erik Larson's "Devil in the White City," a story of Chicago's 1893 World's Fair that tells of architect Daniel Burnham and serial killer H.H. Holmes. Along with Burnham, Stanford says interest piqued in Chicago architects Frank Lloyd Wright and his Prairie Style, Louis Sullivan and his ornate facades, and Ludwig Mies van der Rohe, known for a sleek, modern design.
"People like to see something by these people," Stanford says. He gets questions about what the architects were like as people during his tours, he adds. "It sort of connects them to them. They were all great characters."
More than a century later, Chicago architecture continues to welcome groundbreaking designs, said Mark Sexton, whose Chicago firm Krueck and Sexton designed Millennium Park's Crown Fountain and the Spertus Institute of Jewish Studies.
He says today's architects look to the city's historic buildings to inspire the future.
"Here's a great opportunity not to be timid," Sexton said. "Because Burnham and Sullivan and Wright were not timid. They were pushing the limits of technology and thinking. We thought we should do the same thing."
He said Chicago is special because classic and modern buildings complement each other.
"The two can coexist, each one making the other better," he said. "That's what architecture leaves. It leaves an indelible print."
If You Go...
BOAT: Chicago River cruises take tourists on open-air boats with enclosed lower decks, and sometimes, bars. Cruises sail by Chicago standbys, the Merchandise Mart, Tribune Tower, Sears Tower and the corn cob Marina Towers, led by knowledgeable docents.
BICYCLE: The Architecture Foundation offers three-hour bicycle tours from Millennium Park along Lake Michigan, and covers the museum campus, Soldier Field and Northerly Island. Bring your own bike or rent one. Adults, $10; students and seniors, $5.
BUS: The Architecture Foundation offers a dozen different bus tours covering the city. The most popular is "Highlights by Bus" takings tourists 30 miles through the Loop, Hyde Park and Gold Coast. Daily tours, adults, $40; seniors and students, $35.
ON FOOT: The Chicago Architecture Foundation offers more than 60 different walking tours of the city's buildings, featuring tours by specific architect, neighborhood, cemetery, street or skyscraper. Tours priced $5-20.
ASSORTED: The foundation also offers happy hour tours, lunchtime lectures and tours in foreign languages. It also has a museum with permanent and rotating exhibitions and a lecture hall. Details from Chicago Architecture Foundation, 224 S. Michigan Ave., Chicago; http://www.architecture.org or 312-922-3432; open daily 9 a.m.-5 p.m.