There's a "castle" with two areas, both of which contain four mazes. In between the areas is a tower with a laser.
On top of that tower, there are two puzzles. The first requires the solutions to the first area an actives the laser. To solve the second puzzle, you actually don't seem to need to have solved the mazes in the second area (although I have). I've solved this second puzzle on top of the tower, but I didn't notice any effect of solving this.
So, does solving the second puzzle on top of the tower trigger anything?
BTW, I didn't notice any effect of having solved the fourth puzzle in the second area (the puzzle with two "L" pieces). Did it enable the second tower puzzle?