Police were forced to shut Whitehall in central London on Friday afternoon after a man climbed on top of a statue and took all his clothes off.
The unnamed nude man straddled a statue of a horse ridden by Prince George, a former Duke of Cambridge and field marshall, at the Trafalgar Square-end of the road.
Initial reports had suggested the man may have a knife, however a Scotland Yard spokesperson said they had not been "made aware of any knife."
Police at the scene said it was unclear what the man's motive was.
Whitehall runs from Trafalgar Square to Parliament and is the site of many government departments including the Ministry of Defence and connects with Downing Street.
A police officer at the scene told the Huffington Post UK that the man climbed up the statue fully clothed, then proceeded to take them off.
A bystander said: "I can't believe they've cordoned off the whole street for one naked man, it's ridiculous!".
The man could be seen adopting a variety of poses on the statue, which is of Prince George, the Duke of Cambridge.
At times he was balancing precariously on the duke's head with both arms outstretched.
A Metropolitan Police spokesman said: "Police were called shortly after midday to reports of a man who had climbed on a statue in Whitehall, near the junction with Horse Guards Avenue.
"Officers are on scene and are attempting to engage the man in dialogue, with a view to bringing the incident to a peaceful and successful conclusion."