On top of the Haunted Mansion there are chess pieces - couple of pawns, rooks, kings, queens, etc. - decorating the roof like mini-towers. The chess pieces are there because the building's architect and attraction's chief designer loved chess. All of the pieces are there accept for one which is a knight. The reason there is no knight chess piece on the roof of the mansion is because it is always "night" inside the Haunted Mansion. the mansion is built this way as a pun: chess is the GAME OF LIFE!