Hamilton was born in Lanarkshire and educated at Glasgow University. He travelled to Rome in 1748 to study painting under Agostino Masucci. He returned to London in 1751 but decided to settle permanently in Italy in 1756 and was to remain there for the rest of his life. Hamilton's huge neoclassical paintings, with their subject matter taken from Homer and their style influenced by both Poussin and the Antique, were of fundamental importance to the development of European art. He was also active as an archaeologist and dealer, and was a friend and guide to many visiting artists and patrons.