Nairobi is the capital and largest city of Kenya. The city and its surrounding area also form the Nairobi County. It is popularly known as the “Green City in the Sun” and is surrounded by several expanding villa suburbs. Nairobi is now 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 organizations, including the United Nations Environment Programme (UNEP) and the main coordinating and headquarters for the UN in Africa and 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. It is Africa’s fourth largest exchange in terms of trading volume, capable of making 10 million trades a day. The Globalization and World Cities Study Group and Network (GaWC) defines Nairobi as a prominent social center. Top sights include the Karen Blixen Museum, Giraffe Center and the black rhinos of Nairobi National Park. The compact city center is safe to walk in and taxis make other areas accessible.