Which of these team sports is played on the largest outdoor pitch?

Polo is a horseback mounted team sport. It is one of the world's oldest known team sports. Polo has been called "the sport of kings". It has become a spectator sport for equestrians and society, often supported by sponsorship.

The concept of the game and its variants date back from the 6th century BC to the 1st century AD. The sport originated from equestrian games played by nomadic Iranian peoples . Polo was at first a training game for cavalry units, usually the Persian king’s guard or other elite troops. A notable example is Saladin, who was known for being a skilled polo player which contributed to his cavalry training. It is now popular around the world, with well over 100 member countries in the Federation of International Polo. It is played professionally in 16 countries.

The playing field is 300 by 160 yards (270 by 150 m), the area of approximately six soccer fields or 9 American football fields (10 acres), while arena polo is 96 x 46 metres. The playing field is carefully maintained with closely mowed turf providing a safe, fast playing surface. Goals are posts which are set eight yards apart, centred at each end of the field. The surface of a polo field requires careful and constant grounds maintenance to keep the surface in good playing condition.