Puzzles for opening hidden doors - Suggestions

Hello. Does anyone have any good puzzles that, upon success, would open a hidden door? The setup up is an open-air shrine in the forest. in a clearing, there's a large stone floor and pieces commemorating a heroic act of villagers from long ago. I want there to be a puzzle for the players to complete that would open the center of the stone floor to reveal a cavern below. Thanks!