The Dark Sky Park feature at Cawfields Quarry on Hadrian's Wall shows how the sky rotates during the seasons. Notice that the patterns have moved by 90 degrees every quarter of a year.
This is because the Earth has moved to a different position relative to the Sun. The constellations revolve every night because of the turning of the Earth about its axis. But these pictures are all set for roughly the same time at night so it rules out the spinning of the Earth. The sign is clever because it is a rectangular box that rotates to give you the season that you want.
