It's about Time: How Long History Took

- 1/400th of a second--photographing the flag-raising on Iwo Jima (1945)
- Two hours, 32 minutes--Neil Armstrong's walk on the moon (1969)
- Four days--stock market crash (1929)
- 14 years, 28 days--the carving of Mount Rushmore (1927-41)
- 2,267 years--construction of the Great Wall of China (7th century B.C.-1568)