Ulaanbaatar
Ulaanbaatar, formerly anglicised as Ulan Bator (, , literally "Red Hero"), is the capital and largest city of Mongolia. The city is not part of any aimag (province), and its population was over 1.3 million, almost half of the country's total population. Located in north central Mongolia, the municipality lies at an elevation of about in a valley on the Tuul River. It is the country's cultural, industrial and financial heart, the centre of Mongolia's road network and connected by rail to both the Trans-Siberian Railway in Russia and the Chinese railway system.
Apostolic Prefecture of Ulaanbaatar
The Apostolic Prefecture of Ulaanbaatar () is a Roman Catholic Latin apostolic prefecture (pre-diocesan missionary jurisdiction) located in (Outer) Mongolia, with its territory consisting of the entire country. 
Its cathedral episcopal see is the Cathedral of Saints Peter and Paul, in the capital city of Mongolia, Ulaanbaatar.