The architecture of the Indian state of Rajasthan has usually been a regional variant of the style of Indian architecture prevailing in north India at the time. Rajasthan is especially notable for the forts and palaces of the many Rajput rulers, which are popular tourist attractions. Most of the population of Rajasthan is Hindu, and there has historically been a considerable Jain minority; this mixture is reflected in the many temples of the region. Māru-Gurjara architecture, or "Solaṅkī style" is a distinctive style that began in Rajasthan and neighbouring Gujarat around the 11th century, and has been revived and taken to other parts of India and the world by both Hindus and Jains. This represents the main contribution of the region to Hindu temple architecture. The Dilwara Jain Temples of Mount Abu built between the 11th and 13th centuries CE are the best-known examples of this style. The Adhai Din Ka Jhonpra mosque in Ajmer (no longer in religious use) is an important early example of Indo-Islamic architecture in a state not otherwise notable for this; though the Ajmer Sharif Dargah is another early building. The generally arid climate has made stepwells (baoli or bawdi) more common than in other parts of India, as well as the distinctive covered taanka underground tanks. Stone carved jali screens are very common, both in temples and secular buildings. As well as palaces, many cities have surviving large townhouses or haveli from the last few centuries. List of palaces in Rajasthan The Hill Forts of Rajasthan (Amer, Chittor, Gagron, Jaisalmer, Kumbhalgarh, Ranthambore), a group of six forts built by various Rajput kingdoms and principalities during the medieval period are among the best examples of Rajput Architecture. The ensemble is also a UNESCO World Heritage Site. Other forts include the Mehrangarh Fort and Jaigarh Fort. The walled city of Jaipur was formed in 1727 by Jai Singh II, and is "a unique example of traditional Hindu town planning", following the precepts set out in much older Hindu texts.