Single Form is an abstract sculpture by British artist Barbara Hepworth. Hepworth was commissioned by Jacob Blaustein, former U.S. delegate to the United Nations, to make the sculpture as a memorial to the late UN Secretary-General Dag Hammarskjold after his death in an air crash in Africa in 1961. 
  
The sculpture is a free-form abstraction, broadly oval, irregular in shape, and pierced near the top by a circular hole. Many interpretations of it have been offered, such as it being a profile of with an eye, a human hand raised in salute or gesture of allegiance, or an expanse of space in which the sun rises. 
  
The artist herself has not offered any concrete interpretation of her other work, but said of the sculpture: “Throughout my work on the ‘Single Form’ I have kept in mind Dag Hammarskjold’s ideas of human and aesthetic ideology and I have tried to perfect a symbol that would reflect the nobility of his life, and at the same time give us a motive and symbol of both continuity and solidarity for the future.” 

Dag Hammarskjold had often privately expressed the wish that the circle in front of the Secretariat Building at U.N. Headquarters would one day be adorned with an appropriate sculpture.  He suggested Barbara Hepworth, whose work he greatly admired, to create the sculpture.  
 
The sculpture was unveiled at the United Nations headquarters during a ceremony presided over by Secretary-General U Thant on 11 June 1964.