Though Buddhist ritual spaces vary a great deal architecturally and decoratively from one region to another, a number of commonly used signs and symbols appear. Perhaps the single most important is the eight-spoked Wheel of Dharma, reminder of the Four Noble Truths and the Eightfold Noble Path. Tibetan temples identify themselves with a characteristic form of the classical Indian stupa called a chorten, a five-level architectural form crowned with a conical shape. Chinese Buddhist temples borrowed their ground plans from the traditional royal residence, a walled enclosure with one or more interior courtyards surrounding the main sacred structures. The principal inner structures face south and are lined up on an axis with the main gate. A multistoried polygonal pagoda may be part of the complex. Japan largely borrowed the classical Chinese ground plan, varying the placement of the inner buildings somewhat. Always found at the back of the walled enclosure is the main image hall where central rituals occur. Three-, five-, or seven-story square pagodas are a regular feature in the main courtyard of many Japanese temples. Thai temples feature a very distinctive roofline and post very imposing guardian figures before the main door, but do not generally have separate pagoda structures.