Located in Zhouzhi County, southwest of Xi'an, Louguantai is the place where Taoist ancestor Lao Tzu preached. More than two thousand years ago, Yin Xiguan, an official of Hangu Pass, was dissatisfied with the decline of Zhou's Royal family, and went to the end of Nanshan to build a grass building, intending to stay away from the world. Suddenly one day, when he saw the purple air coming eastward, he felt deeply that a saint was coming. He rushed to Hangguguan, where he had indeed waited for Laozi. Yin Xi invited Lao Tzu to write the Tao Te Ching, and worshipped it as a teacher. He invited Lao Tzu to give a lecture on Tao Te Ching at the end of Nanshan Mountain, leaving behind such relics as today's lecture platform and alchemy stove.