In 1458, the king at the time in Amberg died, and his son (the heir) was adopted by his uncle. The uncle tried to name himself as king, rather than granting the position to his nephew. The people of Amberg revolted, demanding that the son of the king assume his rightful place on the throne. Three particularly outspoken men were beheaded because of this. They are considered to be heroes of Amberg.
The plaque states that whoever strokes one of these decapitated heads will be beholden to Amberg and will be sure to return again someday.
We certainly plan on coming back to Amberg, but I thought I’d make doubly sure!