This statue depicts Hadrian nude, in the guise of Mars, the god of war, using a well-known classical body type of the divinity; the Ares Borghese, attributed to the Greek sculptor Alcamenes. Hadrian was the first emperor to be represented in this manner.
The statue shows characteristics of early versions of Hadrian’s portrait type, indicating that it was sculpted at the beginning of Hadrian’s reign, between 117 and 125 AD.
Source: Hadrian: Empire and Conflict by Thorsten Opper / Les portraits d’Hadrien. Typologie et ateliers by Cécile Evers