Introduction to Peeping Sun Tower: Behind the "Sundial" Square are the "Main Sign Tower" and "Main Sign Pavilion" attractions. The "Main Mark Tower" is 23.26 meters high, which is consistent with the geographical latitude of the Tropic of Cancer. There is a "peep hole" on the top of the tower. On the summer solstice every year, you can watch the spectacle of "the pole disappears" from here.