The Dying Gaul

 Also at the National Gallery is the sculpture, the Dying Gaul (c. 1st-2nd century CE).

 It's on loan from Italy, the first time ever (the only other time it left Rome was in 1797 thanks to Napoleon, but that bad boy had to return in 1816, and it was hardly a "loan"!) It's just shy of 2,000 years old, and arguably the finest work of art from the Roman Antiquity (Okay, there is David in Florence...) It's on display on the north edge of the grand rotunda in the west building. It is magnificent.

You'll find it on the north end of the grand rotunda...surrounded by visitors.