When the witch built the 40-flight tower, she made very sure to do the whole thing properly. Each flight contains a dreadful monster, ranging from a diamond-scaled dragon to a pack of slavering goblins. Should a prince battle his way to the top, he will be rewarded with a golden sword - and the lovely Princess Floralinda.
But no prince has managed to conquer the first flight yet, let alone get to the 40th.
In fact, the supply of fresh princes seems to have quite dried up.