On April 20, 1861, an estimated 100,000 people hosted what the New York Times called a "mass meeting" in New York City's Union Square to "uphold the authority of the Government" after the attack on Fort Sumter that started the American Civil War. At the time, this was the largest public gathering ever orchestrated in the U.S. In the wake of the 9/11 attacks, the square was lined for days with wreaths and candles left behind by New Yorkers, who had gathered to mourn the horrifying assault on their city.
Top 10 Famous Protest Plazas
For almost two weeks, Cairo's Tahrir Square has been flooded with Egyptians demanding an end to Hosni Mubarak's government. TIME takes a look at plazas and public squares in other world cities that played host to tremendous scenes of political upheaval