Why are the Parthenon sculptures divided?

The sculptures were made as parts of the Parthenon, a temple on the Acropolis in Athens. Their original setting joined carved figures to a building and to one another. In a museum gallery you can study surviving surfaces close up, while their separation from that building remains part of what you are looking at. Most surviving sculpture is divided between London and Athens, with fragments elsewhere. The debate concerns that division, the circumstances of removal and what kind of display should follow. It has a documented chronology and different institutional positions.