The Altar of Heaven (Huan Qiu Tan) at Tian Tan.



The Altar of Heaven is constructed of three tiers of green and white marble, the circumference of each tier being fitted with a white marble balustrade. The surface of the platform, the stairs and the railings are made up of stone slabs in multiples of nine. This is drawn from the ancient Chinese belief that nine was the numerical epitome of Yang, the positive force, and symbolized Heaven. The top platform is 33.3 meters in diameter and has a circular stone in the center, which was considered the most sacred spot in the Chinese empire. The first ring of stones around it consists of nine slabs, the second ring of 18, the third of 27 and forth until we reach the ninth and outermost row which consists of 81 slabs. Like the top level, the central and lower levels are each made up of nine concentric rings of slabs which again being laid out in multiples of nine.