Cheomseongdae Observatory Tower


Built during the reign of Queen Seondeok of the Shilla Kingdom, this is
the oldest astronomical observatory and the only stone structure of its kind in Asia.  The granite-made observatory is 9.17 meters high, 3.1 meters in diameter at the top and 5.17 meters in diameter at the bottom. Twenty-seven layers of hexahedral granite stones were built up to form
a cylindrical, bottle-shaped tower on a square base, which is 5.35 meters at each side.
A square top made of long stone bars on top of each other surmounts
the hollow structure. A total of 365 stones were used in its construction.
The number coincides with the days of a year, and the height of each layer is 30 cm. Though it appears to lean somewhat the northeast, it is one of the best preserved Shilla relics. The unique observatory was designated as National Treasure No. 31.