Sanmenxia.

Sanmenxia was built where the Yellow River leaves the mountains and turns north, and everything here is organised around that bend. West of the city, at Hangu Pass in Lingbao, the old road running west to Chang'an and east to Luoyang narrows between a plateau and a ravine; the municipal government describes it as the sacred place where Laozi wrote the Daodejing, and it still names the pass's own buildings, from the Tai Initial Temple to the Chicken Crow Terrace. In the city itself, the Guo state tomb field at Shangcunling supplies a written record of a small Western Zhou kingdom that once guarded the western approach, with bronze vessels carrying the owner's name and chariot pits that show its military household. Along the river, the Swan Lake urban wetland park keeps an 8,850-mu stretch of the city where tens of thousands of white swans arrive each autumn to winter on the water.