Thousands of people gather on Norlin Quad at the University of Colorado in Boulder, Colorado, where the April 20 date has been famously marked for years. This photo was taken at precisely 4:20 PM, when the entire crowd exhaled at once.
Residents of Kibera, one of the poorest quarters in Nairobi gather to watch the inauguration ceremony of US President Barack Obama in Nairobi on January 20, 2009. (YASUYOSHI CHIBA/AFP/Getty Images)
The World Reacts to President Obama (20 photos) - My Modern Metropolis
