Ulaanbaatar, Mongolia's capital and largest city with 1.73 million residents, holds distinction as world's coldest national capital with winter temperatures plunging below -40°C while summer heat reaches 30°C, creating extreme continental climate. The city accounts for nearly half of Mongolia's 3.5 million total population, concentrating economic activity, government administration, and cultural institutions in sprawling metropolis surrounded by mountains and vast steppe grasslands. Founded in 1639 as Da Khure monastery for Tibetan Buddhist leader Bogd Zanabazar, the settlement moved locations multiple times before establishing permanent site in current valley, with modern name "Ulaanbaatar" (Red Hero) adopted in 1924 following communist revolution establishing Mongolian People's Republic aligned with Soviet Union. The capital resides near historic sites including 2,000-year-old Xiongnu royal tombs and 8th-century Turkic inscriptions, though Genghis Khan established his empire's capital at Karakorum rather than present city.

Contemporary Ulaanbaatar faces severe air pollution from ger (traditional felt tent) districts where residents burn coal for winter heating, creating toxic smog during cold months when temperature inversions trap smoke in valley. Rapid urbanization brought rural migrants seeking employment, overwhelming infrastructure and creating sprawling informal settlements lacking municipal services. The economy depends on mining sector exporting copper, coal, gold to China, government administration, services, and manufacturing. Challenges include pollution crisis threatening public health, housing shortages, traffic congestion from vehicle growth, unemployment, and climate vulnerability as warming threatens traditional pastoral nomadic livelihoods driving continued migration to capital. Yet Ulaanbaatar maintains cultural vitality through Buddhist monasteries, museums preserving nomadic heritage, throat singing traditions, and contemporary arts scene navigating tension between modernization and cultural preservation. The city represents post-communist transition economy depending on natural resource exports, urbanization pressures overwhelming provincial capital infrastructure, and climate extremes creating unique adaptive challenges.