Chicago, Illinois

1871Great Chicago Fire: A fire burned for three days, destroying 17,000 buildings, killing 300 people, and leaving 100,000 homeless. Chicago rebuilt in just two years, bigger and better than before.

1886Haymarket Affair: A bomb explosion during a labor rally in Haymarket Square killed seven police officers and four civilians. The trial and execution of anarchist leaders galvanized the international labor movement and led to May Day.

1893World's Columbian Exposition: Chicago's World's Fair introduced the Ferris wheel, the Midway, and the 'White City' to 27 million visitors, establishing Chicago as a world-class city.

1929St. Valentine's Day Massacre: Al Capone's gang gunned down seven rivals in a Lincoln Park garage on February 14, making Chicago synonymous with Prohibition-era organized crime.

1942First Nuclear Reaction: Enrico Fermi achieved the first controlled nuclear chain reaction at the University of Chicago, ushering in the atomic age.

1885First Skyscraper Built: The Home Insurance Building, designed by William Le Baron Jenney, became the world's first skyscraper using steel-frame construction, launching the architecture that defines modern cities.

1968Democratic Convention Riots: Police clashed violently with Vietnam War protesters outside the Democratic National Convention, creating televised chaos that the Walker Report called a 'police riot.'.

1919Chicago Race Riot: A week of racial violence killed 38 people and left over 1,000 Black families homeless after a Black teenager was stoned to death for swimming in 'white' waters of Lake Michigan.

2008Obama's Victory Night: Barack Obama, a Chicago community organizer and senator, celebrated his presidential election victory before 240,000 people in Grant Park.

1900Chicago River Reversed: Engineers reversed the flow of the Chicago River to carry sewage away from Lake Michigan — one of the most ambitious engineering projects in American history.