A 40-year-old piece of wedding cake will hit the auction block in about two weeks . . . and it's expected to sell for around $700.
Why? Because it was from the wedding of Prince Charles and Princess Diana in July of 1981. The slice came from one of 23 cakes that were made for the ceremony.
It comes with a wedding program, ceremony details, and a breakfast menu. It was last sold in 2008.
The auction house says, quote, "It appears to be in exactly the same good condition as when originally sold. But we advise against eating it."