25 -- Number of windows in the Statue of Liberty's crown, all hand-produced in 1986 by Pittsburgh's Traco Co., to assist in Lady Liberty's 'facelift.'

2,000 -- Number of passengers that could be carried in the railroad car-sized gondolas of the original Ferris Wheel, invented by Pittsburgher George Ferris in 1892 for the World Columbian Exposition (Ferris had been challenged to create a signature structure that would eclipse the Eiffel Tower, which was unveiled at the Paris Expo in 1889).

50 -- Cost, in cents, for three months of swimming at the Carnegie Library of Homestead's indoor pool in 1932, where Olympic swimming champions Anna Mae Gorman and Lenore Kight trained.

Plenty of Pittsburgh people have left their mark on the world's social, cultural, political and economic landscape. Here's a sampling, from A to Z.

We all want to change the world. Here are five Pittsburgh contributions that did:

The Polio Vaccine -- Jonas Salk tested the experimental polio vaccine on monkeys, himself, his colleagues at the Virus Research Laboratory at the University of Pittsburgh, his wife, his children, and students at the D.T. Watson Home for Crippled Children and the Polk School before a national field trial was held in 1954 involving nearly 1.8 million children nicknamed "Polio Pioneers."

It took a year to evaluate the results of the trial, and on April 12, 1955, pandemonium broke out when his vaccine was declared "safe, effective and potent." Within two years, polio cases -- which had reached epidemic levels of nearly 60,000 in 1952 -- dropped 90 percent.

Alternating Current -- George Westinghouse knew there was an alternative to direct current and its limited value in powering cities. With Nikola Tesla, he developed alternating current, which could be distributed over long distances with high voltages without losing power, and could also be converted to low voltages to safely light homes and appliances.

Despite the obvious benefits of the new technology, powerful critics emerged. Westinghouse's fiercest rival -- Thomas Edison -- attempted to sway public opinion by developing the AC-powered electric chair, electrocuting animals, and buying full-page advertisements showing the negative effects of alternating current, which he called the "current of death."

Ultimately, Westinghouse won the "battle of the currents," and changed our world forever.

Business Breakthroughs -- From Alcoa to U.S. Steel to Heinz, America's most innovative companies changed the world from Pittsburgh.

Alcoa's aluminum enabled air travel, lunar exploration, and the world's first successful airplane for the Wright Brothers (not to mention an aluminum bikini and Oscar de la Renta dress). U.S. Steel, with its production might and innovations in vertical integration and specialty steel, enabled the world's first skyscrapers and cemented Pittsburgh's reputation for industrial might. And Heinz, doing so many common things uncommonly well in the food business, also used its influence to push through the Pure Food and Drug Act of 1906, a revolutionary accomplishment for the safety of the American people.

Entertainment and Communication Innovations -- Pittsburgh innovations laid the foundation for the world's most ubiquitous mass media entertainment options -- radio, television, and the movies.

In 1905, Pittsburgh entertainment entrepreneur John P. Harris opened the Nickleodeon, the first theater dedicated entirely to showing movies -- for 5 cents, of course.

KDKA became the first radio station to transmit a commercial broadcast on November 2, 1920, when it shared the election results of the presidential race between Warren Harding and James Cox. The results -- Republican Harding and his running mate Calvin Coolidge won -- were said to be heard as far away as Canada.

WQED broadcast for the first time on April 1, 1954, as the first community sponsored educational TV station in the country.

And our renowned university community has picked up where earlier innovators left off, with technology advancements that have changed the way the world communicates. They range from astounding advances in computer science and artificial intelligence, all the way to the consumer level: Carnegie Mellon University professor Scott Fahlman's emoticons: :-) and :-(

Rachel Carson and the Modern Environmental Movement. Rachel Carson, who grew up along the banks of the Allegheny River in Springdale, lived in the shadow of Pittsburgh's belching smokestacks and their environmental ravages. She wrote "Silent Spring" in 1962, challenging prevailing practices and calling for change in the way people view the natural world. Even in the face of ridicule and resistance by the U.S. Department of Agriculture and the pesticide industry, Carson focused unprecedented attention on the issue of unrestricted chemical spraying, which resulted in the eventual ban of DDT.

Today, Pittsburgh's environmental conscience is a model for the country in areas such as green building and design. Pittsburgh also led the nation in clean air legislation while cleaning up the "smoky city."

What more is there to know about quintessential Pittsburgh stuff?

Many of Fred Rogers' classic cardigan sweaters, worn on the nearly 1,000 episodes of "Mr. Rogers' Neighborhood," were sewn by his mother, Nancy McFeely Rogers.

Favorite son.

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Built in 1870, the Mon Incline is the world's oldest continually operating plane railroad, and -- at 635 feet -- is also the world's steepest. At one point in Pittsburgh's history, there were 16 additional inclines across our hilly terrain.

While the Jack Rabbit, Thunderbolt and Racer are modern-day Kennywood classics, dozens of coasters have thrilled the crowds at Kennywood over its more than a century in operation, including the Pippin, Speed-O-Plane, Teddy Bear and Dipper.

Pittsburgh's most famous boomers, the Zambellis, produce more than 3,500 firework shows every year, using handmade shells that range in size from a tennis ball to a basketball, and can fly as high as 1,500 feet. Special displays have entertained every president since John F. Kennedy.

Jim Delligatti created the legendary Big Mac in 1967 at his McDonald's in Uniontown. It was almost ignored for a preferred sandwich suggested by the corporate office: pineapple and cheese.

Pittsburgh's five Super Bowls, five World Series, and two Stanley Cup victories run through our blood. But countess barriers broken throughout our sporting history have nourished the city's soul. A few highlights:

When the Pirates starting nine ran onto the field on Sept. 1, 1971, most of the players didn't realize they were making history. Pirates Manager Danny Murtaugh fielded Major League Baseball's first all-minority starting lineup against the Philadelphia Phillies, including five African Americans, two Panamanians, one Puerto Rican and one Cuban player. The Pirates beat the Phillies 10-7 that day.

Oscar Charleston

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Pittsburgh was the only city with two Negro League teams, the Pittsburgh Crawfords and Homestead Grays. With Hall of Famers like Cool Papa Bell, Josh Gibson, and Satchel Paige, the two teams combined for more than a dozen Negro League championships, with the Grays winning nine straight (1937-1945). (Pictured at right, Oscar Charleston.)

Born in 1930 in New Kensington, Willie Thrower was the first African-American quarterback in the modern NFL, playing for the Chicago Bears for $8,500 in 1953. It was 14 more years before another African-American quarterback played for a NFL team.

Surprising stories -- and Pittsburgh ingenuity -- underlie some of the city and the country's most famous structures.

While St. Louis needed a symbol to identify it as the "Gateway to the West," Pitt-Des Moines Steel Co. on Neville Island fabricated the 900 tons of stainless steel and oversaw the assembly of the St. Louis Arch, completed in 1965.

In 1914, Pittsburgh companies built the steel gates and search lights for the Panama Canal, one of the most difficult engineering projects ever undertaken.

Thanks, Pittsburgh.

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U.S. Steel's American Bridge Co. and Pittsburgh's McClintic Marshall Co. transported 60,000 tons of steel via trains, barges and trucks to New York City to build the Empire State Building (at right) in 1931.

The Civic Arena, with the world's first -- and largest -- retractable dome roof, was originally built to house the Civic Light Opera.

When Duquesne Gardens opened in Oakland in 1899, it featured the world's largest indoor ice rink and hosted the world's first semi-pro hockey league, the American Hockey League. At 26,000 square feet, it dwarfed all other existing rinks.

The inspiration for the University of Pittsburgh's Cathedral of Learning came from Chancellor John Bowman, who was shocked, upon his arrival to Pittsburgh, to discover that his streetcar driver was unaware of the city's largest university. The world's first university skyscraper, the Cathedral of Learning hosted its inaugural class in 1931.