What is a "three walls"

"The historical records, day GuanShu" will see north celestial pole piece of the sky on the earth is divided into Chinese, too, day, this is known as "three walls".Pole-ziweiyuan is slope in the three walls, in central north day, say again so the palace, or Chinese palace.The Chinese palace the imperial palace

Meaning, each star most named after the prime minister.Too small a slope is on three walls, walls, top Yu Ziwei slope beneath northeast, south of beidou.Star is too small, the government also use named after the prime minister, namely TingWei left law enforcement, for example, law enforcement is of the right, etc.Day the city walls is three walls under the rubble, in the southeast under pole-ziweiyuan, day, namely the bazaar, the day the Book of Jin, chinese-speaking, cloud: "son of heaven rate leud xing city also."Therefore, star, star of multi-purpose goods business named after content market.Pole-ziweiyuan including the region near the north celestial pole, roughly equivalent to the circumpolar stars area;Too small walls including constellation virgo, backwardness, lion's part;Day the city walls, including the serpent, caption, serpent, part of the constellation skyhawk etc.