The flags of the 193 United Nations Member States provide a colourful, 500-foot wide curved approach to the Headquarters, along United Nations Plaza. The circular pool in front of the Secretariat Building, with a fountain in its centre, was built with a $50,000 gift from the children of the United States. The wavy pattern on the floor of the pool is formed by alternating bands of crushed white marble and black pebbles. The black stones were gathered from the beaches of Rhodes by the women and children of that Greek island, and donated to the United Nations. A bronze sculpture in memory of the late Secretary-General, Dag Hammarskjöld, was set at the edge of the pool in 1964. The abstract sculpture, entitled Single Form, is the work of the English modernist sculptor and artist, Barbara Hepworth, and was donated by Jacob Blaustein, a former United States delegate to the United Nations.