23. Prince Charles and Princess Diana - 1981
Estimated Cost: $110 million
Okay, so this figure is adjusted for inflation since it happened in 1981, but still. It was watched by an estimated 750 million people around the world and there were 3,500 guests in attendance at St. Paul's Cathedral. Princess Diana's dress featured a 25-foot train and her dress was covered in 10,000 pearls to boot. Oh, and they had 27 wedding cakes.