On May 31, 455 A.D., Emperor Petronius Maximus was stoned to death by an angry mob while fleeing Rome.
On that date in 1578, King Henry III laid the first stone of the Pont Neuf (New Bridge), the oldest bridge of Paris, France.
In other rock history, May 31, 2013, marked the closest approach to Earth that the asteroid 1998 QE2 and its moon will get until two centuries hence.