Bangkok is the capital and most populous city of Thailand. It is known in Thai as Krung Thep Maha Nakhon or simply Krung Thep. The city occupies in the Chao Phraya River delta in Central Thailand, and has a population of over 8 million, or 12.6 percent of the countrys population. Over 14 million people live within the surrounding Bangkok Metropolitan Region, making Bangkok an extreme primate city, significantly dwarfing Thailands other urban centres in terms of importance. Bangkok traces its roots to a small trading post during the Ayutthaya Kingdom in the 15th century, which eventually grew and became the site of two capital cities: Thonburi in 1768 and Rattanakosin in 1782. Bangkok was at the heart of the modernization of Siam—later renamed Thailand—during the late 19th century, as the country faced pressures from the West. The city was at the centre of Thailands political struggles throughout the 20th century, as the country abolished absolute monarchy, adopted constitutional rule and underwent numerous coups and several uprisings. The city grew rapidly during the 1960s through the 1980s and now exerts a significant impact on Thailands politics, economy, education, media and modern society. The Asian investment boom in the 1980s and 1990s led many multinational corporations to locate their regional headquarters in Bangkok. The city is now a major regional force in finance and business. It is an international hub for transport and health care, and has emerged as a regional centre for the arts, fashion and entertainment. The city is well known for its vibrant street life and cultural landmarks, as well as its notorious red-light districts. The historic Grand Palace and Buddhist temples including Wat Arun and Wat Pho stand in contrast with other tourist attractions such as the nightlife scenes of Khaosan Road and Patpong. Bangkok is among the worlds top tourist destinations. It is named the most visited city in MasterCards Global Destination Cities Index, and was named "Worlds Best City" for four consecutive years by Travel + Leisure magazine. Bangkoks rapid growth amidst little urban planning and regulation has resulted in a haphazard cityscape and inadequate infrastructure systems. Limited roads, despite an extensive expressway network, together with substantial private car usage, have led to chronic and crippling traffic congestion, which caused severe air pollution in the 1990s. The city has since turned to public transport in an attempt to solve this major problem. Five rapid transit lines are now in operation, with more systems under construction or planned by the national government and the Bangkok Metropolitan Administration.