Construction on the bridge began in January 1933. Workers excavated 3 1/4 million cubic feet of dirt to make way for the bridge's anchorages, one on each side of the Gate.

The first 745-foot tower began to rise in Nov. 1933. Prefabricated sections were fit into place and then joined together by four-man rivet gangs. The heater was the boss; he brought rivets to the right temperature on a small forge, then tossed them to catchers with metal cans.

Working twelve to fourteen hours a day, Charles Ellis personally computed dozens of factors, and completed the bridge's overall design in four months. In November 1930, Strauss directed Ellis to begin the thousands of detail calculations involving suspension ropes, decks, floor beams, highway track, cables, towers, and more.

Chief Engineer Joseph Strauss hired a local architect, Irving Morrow, to design an architectural treatment for the bridge. Morrow would later be recognized for his aesthetic contributions: the Golden Gate Bridge's distinctive Art Deco lines, burnt red-orange hue, and the structure's dramatic lighting.

Emma Goldman's anarchist politics and outspoken activism against capitalism, wars, and the oppression of women captivated and polarized the American public for nearly thirty years.

American Anarchists in the 1880s were a small but powerful movement who advocated radical ideals of universal human equality, education for all, and an end to state government.

In June 1892, workers at the Andrew Carnegie-owned steel plant in Homestead, Pennsylvania went on strike. When plant manager Henry Clay Frick hired 300 armed guards to attack strikers, the resulting battle ended in deaths on both sides.

The Panic of 1893, a severe economic depression, created public awareness of the growing gap between the rich and the poor. Emma Goldman organized demonstrations and encouraged unemployed Americans to demand jobs and food from the wealthy.

In May 1917, Emma Goldman and Alexander Berkman organized demonstrations protesting America's recent entry into World War I — risking fines and imprisonment as President Woodrow Wilson's administration increasingly cracked down on anti-war resistance.

Emma Goldman defied laws against public discussion of sex and contraceptives, campaigning for birth control as a means of social change and women's empowerment. Beginning in 1908, Emma Goldman toured the country with her partner, Ben Reitman, speaking on anarchism, free love, and other controversial issues.

Psychology professor at the City College of New York, Dr. Kenneth Clark introduces the segment "The Negro and the American Promise" from Boston public television producer Henry Morgenthau III. Featuring interviews with Martin Luther King, Malcolm X, and James Baldwin, the segment made headlines in spring 1963.

Martin Luther King appears in Boston public television producer Henry Morgenthau III's "The Negro and the American Promise," alongside Malcolm X and James Baldwin.

James Baldwin appears in Boston public television producer Henry Morgenthau III's "The Negro and the American Promise," alongside Martin Luther King and Malcolm X. The New York Times described the James Baldwin segment as "a television experience that seared the conscience."

Malcolm X appears in Boston public television producer Henry Morgenthau III's "The Negro and the American Promise," alongside Martin Luther King and James Baldwin. After watching the segment a viewer wrote that he was shocked "that such a blatant display of racial prejudice could be aired."

The design and construction of the twin towers of the World Trade Center marked a dramatic break with nearly a century of skyscraper tradition. The unprecedented height and size of the towers posed a new kind of structural challenge. They needed not only to support the sheer weight of the 1,360-ft-tall buildings, but to overcome the even greater loads caused by the high winds of New York Harbor.

The structures needed not only to support the sheer weight of the 1,360-ft-tall buildings, but to overcome the even greater loads caused by the high winds of New York Harbor pushing against the wide, flat sides of the buildings, especially along their uppermost floors. The solution: a super-strong lattice of exterior steel columns, creating a remarkably stiff "tube" that could resist high winds.

The foundations themselves presented the first challenge. They would have to descend through 70 ft. of water-logged landfill before reaching bedrock. The greatest challenge by far, however, lay in the engineering of the towers themselves. The solution, developed by the structural engineers John Skilling & Leslie Robertson in the mid-1960s, was to re-conceive the basic structure of tall buildings.

As the World Trade Center towers began to rise, another innovation made its appearance. Unlike earlier skyscrapers, assembled one column or beam at a time, the twin towers were erected in huge prefabricated components. Exterior wall sections three stories tall and floor decks 60 feet long could be lifted into place at once. The daring new technique dramatically speeded the construction process.

Before they could sign off on the design for the World Trade Center, engineer Leslie Robertson and his team had to consider all possible events that might take place in a high rise building. One of these possibilities was that of an airplane impact—there had been two incidences of aircraft impact on New York City skyscrapers at that time.

While tunnels were being dug through the limestone and quartzite mountains of Utah, Union Pacific workers laid track in western Wyoming. In the Wyoming desert, temperatures would soar above 100 degrees by day and fall below freezing at night.