Beijing is one of the oldest, and now, one of the most crowded cities in the world. Established as a city in 1045 BC, King Wu was the first to declare it as a capital in 1057 BC. Having served as the capital of the Liao, Jin, Yuan, Ming and Qing Dynasties, Beijing is now the capital of the People's Republic of China. In these Landsat images, the explosive growth of this ancient city is clearly visible. In 1972, only about 7.89 million people lived there — but by 2010 the population swelled to more than 12 million. This increase in the city's size corresponds to the opening of China to the Western world in the 1970s. Up until 1979, the government restricted housing in the city, limiting it to the confines of the "Outer City." Previously a walled fortress, its outline is still visible today due to the build up of canals and roads along the path of the original wall. Inside this rectangular boundary is the ancient heart of the capital, the moat-lined Forbidden City. Called forbidden because anyone entering needed royal permission, this is where the Imperial Palace still stands, once home to 500 years of Chinese emperors. It was Kublai Khan who established the Forbidden City in 1260 A.D. He called it Khanbaliq but Italian explorer Marco Polo called it Cambuluc. It still stands as Beijing's city center. In 1421 the Chinese took the city back and gave it its current name of Beijing. Today, Beijing is only limited by the rugged Taihang Mountains that run to the west and northwest of the city, pushing the population to spread to the south and east across the relatively flat coastal plain.
GCMD keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 22.214.171.124.0