Bukhara (; ; ; ), is one of the cities (viloyat) of Uzbekistan. Bukhara is a city-museum, with about 140 architectural monuments. The nation's fifth-largest city, it had a population of approximately 272,710. Humans have inhabited the region around Bukhara for at least five millennia, and the city has existed for half that time. Located on the Silk Road, the city has long served as a center of trade, scholarship, culture, and religion. UNESCO has listed the historic center of Bukhara (which contains numerous mosques and madrassas) as a World Heritage Site.