Prince Charles and Diana Spencer's 1981 ceremony is one of the most watched and remembered weddings in history. And with over 3,500 people in attendance at St. Paul's Cathedral and over 5,000 police officers needed, it's also no surprise that it's one of the biggest. 750 million folks watched the wedding on TV and another 600,000 lined the streets of London when 20-year-old Diana Spencer (donning her infamous 25-foot train) married Prince Charles. Later in the day, the pair inaugurated the Buckingham Palace balcony kiss. Sadly, the marriage didn't last. The couple separated in 1992 and divorced in 1996. Princess Di later perished in a paparazzi-related automobile accident in 1997.