Nairobi is the largest city in East and Central Africa. Nairobi is one of the most prominent cities in Africa both politically and financially. Home to thousands of Kenyan businesses and over 100 major international companies and organisations, including the United Nations Environment Programme (UNEP) and the main co-ordinating and headquarters for the UN in Africa & Middle East, the United Nations Office in Nairobi (UNON), Nairobi is an established hub for business and culture. The Nairobi Stock Exchange (NSE) is one of the largest in Africa and the second oldest exchange on the continent.