Hadrian (reigned AD 117-138) is famous as the emperor who built the eighty-mile-long wall across northern Britain. It went from the Solway Firth to the River Tyne at Wallsend, 'to separate the barbarians from the Romans' according to his biographer. This head comes from a statue of Hadrian that probably stood in Roman London in a public space such as a forum. It would have been one and a quarter times life-size.
The statue may have been put up to commemorate Hadrian's visit to Britain in AD 122. Hadrian travelled extensively throughout the Empire, and imperial visits generally gave rise to programmes of rebuilding and beautification of cities. There are many known marble statues of him, but this example made in bronze is a rare survival.
How the bronze head came to be in the river Thames is not known. Its removal from the statue may have been a deliberate act of destruction, cast into the river as an act of defiance. Equally, it may have been placed in the water for religious reasons, since many believed that the emperor was a divine being.