The Eight Queens riddle goes as follows: Take 8 pawns, pretend they move as queens, and set them up on the board so that no two queens threaten each other, ie no piece can take another piece in the next move.
My father posed me this riddle when I was young, nad it would be years (nearly a decade) before I found my first solution over tea at a place called "Stern" in Bamberg, Germany.
The riddle has served me as an ice breaker many times over, and is just generally filled with good memories.
Spoiler alert: This link calculates and visualizes all (including rotated) solutions to the eight queens problem, by structuring the solution space as a set of 64 elements from which to draw appropriately filtered 8-combinations.
This is the second version of this program, with a time performance gain of 99.8% over the previous version.