The event marked the first time a World's Fair had been held in the United States and outside of Europe, and purposely coincided with the centennial celebration of the United States as an independent nation.  In 1871, Congress approved Philadelphia as the official site for the Centennial celebration, but allocated no funds and explicitly denied fiscal responsibility for it.  A Centennial Commission was established, with Joseph Hawley as president, which, in turn, created a Centennial Board of Finance to raise $10 million by selling public stock in the venture.  The chief architect for the massive construction project at Philadelphia's Fairmont Park was A. J. Schwarzmann.  In 1874, the Commission dispatched publisher John Forney to Europe to promote international participation in the Centennial.  Two years later, 36 nations from five continents sent representatives to Philadelphia. 

A crowd of 10,000 attended the opening ceremonies on May 10, 1876.  President Ulysses S. Grant formally inaugurated the celebration with a brief speech; Emperor Pedro II of Brazil sat on the podium as the honored guest; the orchestra played the national anthems of 16 countries (in alphabetical order), followed by "Centennial Inauguration March," a specially commissioned piece by Richard Wagner; a 1000-voice choir sang various selections, ending with the "Hallelujah Chorus"; and the ritual concluded with a 100-gun salute as President Grant hoisted a ceremonial flag.  The dignitaries and audience then dispersed into the five primary buildings:  Main Building, Art Gallery (Memorial Hall), Agricultural Hall, Horticulture Hall, and Machinery Hall.  There were over 30,000 displays from the various nations and fifty states.

Like other World's Fairs, the emphasis at the Centennial Exhibition was on the inventions and innovations of technology and applied science.  The Exhibition's technological theme was in full evidence at the gigantic Machinery Hall, which housed 13 acres of gadgets and gizmos.  Visitors could pay 50¢ to have a letter written on a new device called a typewriter.  A startled Emperor Pedro dropped the new "tele-phone," crying out "My God; it talks!"  A popular exhibit was a prototype piece of cable that Washington Roebling planned to use in constructing the Brooklyn Bridge (completed, 1883).  The Woman's Pavilion contained exhibits created by women, including a power loom for weaving cloth and a printing press for The New Century for Women, both operated by women.  Special editions of three New York newspapers--the Herald, Sun, and Times--were printed daily in Machinery Hall during the Centennial.

The featured exhibit at Machinery Hall and the entire Centennial Exhibition was the Corliss Steam Engine, which powered the numerous machines in the large building.  The formidable engine stood 40-feet high, had a 56-foot diameter platform, weighed 200 tons, generated up to 2500 horsepower, and connected to the hall's smaller machines by 5 miles of shafting.  President Grant and Dom Pedro threw a switch to start the motor, as the crowd roared its approval.  Throughout the Centennial, fascinated visitors elbowed their way to see the Corliss Engine, including poet Walt Whitman who sat mesmerized in front of it for 30 minutes.

Agricultural Hall housed machines, tools, and products related to agriculture, animal husbandry, woodcrafts, alcohol production, tobacco curing, textile manufacture, fur- and leather-making, and similar pursuits.  The products ranged from Brazilian nuts to Chinese teas, and the exhibits included a working windmill.  The Smithsonian Institute, which shared the U.S. Government Building with several federal departments, showcased animals (including a walrus and polar bear) and minerals.

Although Horticultural Hall was the smallest of the buildings, it contained the world's largest conservatory at that time.  The building was praised for its Moorish architectural design, with blue marble entrance steps, and reflecting pool outside.  Its interior and exterior galleries, terraces, and gardens displayed thousands of brilliant and exotic flowers and plants from around the world.  Lectures on horticulture were given every Saturday.  

The Art Gallery (Memorial Hall) is the only one of the Centennial's main buildings still standing.  At the time of its construction there were only five buildings in the United States that had been specifically designed to be art museums (as compared with about 30 in Europe).  Most Americans viewed nudes in painting and sculpture (from Europe) for the first time at Memorial Hall.  It created a controversy that helped make the Art Gallery the second-most popular site after Machinery Hall.  Perhaps the most famous painting of the Centennial, Thomas Eakin's The Gross Clinic, a realistic depiction of surgery, was displayed in the medical area of the Exhibition.  

Black Americans were little represented or seen at the Centennial, provoking criticism from Frederick Douglass.  A notable exception was Italian artist Francesco Pezzicar's statue, "The Abolition of Slavery in the United States," which showed a freed slave holding the Emancipation Proclamation aloft.  The Smithsonian and Interior Department featured American Indians in a joint exhibit. Congress refused to allow live Indians to participate, so manikins were displayed, along with baskets, buckskins, canoes, weapons, tools, totem poles, and other artifacts.  News of the Sioux victory over Colonel George Custer and his troops at Little Big Horn arrived during the Centennial.

The Civil War was politely ignored at the Centennial Exhibition, but symbols of the American Revolution were embodied in an original copy of the Declaration of Independence and the Liberty Bell, both at Philadelphia's Independence Hall.  One Exhibition display told the story of the evolution of the American flag, while merchants incorporated eagles and other patriotic symbols into their advertisements.  On July 4, 150,000 people attended an Independence Day extravaganza, highlighted by speakers, brass bands, fireworks, and a reading of the Declaration of Independence.  After the latter, Susan B. Anthony and other suffragists rose in protest to read and distribute their Declaration of Independence for Women.  Bayard Taylor continued reading his poem celebrating the day, while the women were escorted away.