Ulan Bator or Ulaanbaatar is the capital and by far the largest city of Mongolia. An independent municipality, the city is not part of any province, and its population as of 2008 is over one million. Located in north central Mongolia, the city lies at an elevation of about 1,310 metres (4,300 ft) in a valley on the Tuul River. It is the cultural, industrial, and financial heart of the country. It is the centre of Mongolia's road network, and is connected by rail to both the Trans-Siberian  ailway in Russia and the Chinese railway system.The city was founded in 1639 as a movable (nomadic) Buddhist monastic centre. In 1778 it settled permanently at its present location, the junction of the Tuul and Selbe rivers. Before that it changed location twenty-eight times, with each location being chosen ceremonially. In the twentieth century, UlanBator grew into a major manufacturing centre.

Since Mongolia's transition to a market economy in 1990, the city has experienced further growth. In recent years, construction of new buildings has gained new momentum, especially in the city center, and apartment prices have skyrocketed. Ulan Bator is served by the Chinggis Khaan International Airport ,it is 18m southwest of the city. Chinggis Khaan airport is the only airport in Mongolia that offers international flights. Flights to Ulan Bator are available from Tokyo, Seoul, Berlin, Moscow, Irkutsk, Hong Kong, Beijing, Bishkek and Istanbul. 

There are rail connections to the Trans-Siberian railway via Naushki and to the Chinese railway system
 via Jining. Ulan Bator is connected by road to most of the major towns in Mongolia, but most roads in Mongolia are unpaved and unmarked and road travel can be difficult. Even withinn the city, not all roads are paved and some of the ones that are paved are not in good condition.