A man who claimed to be a researcher seeking a private audience with Donald Trump spent three hours scaling the glass facade of Trump Tower using large suction cups before officers hauled him to safety through an open window.
The climber wore a backpack and used a harness and rope stirrups to fasten himself to the side of the 68-storey Manhattan skyscraper on Wednesday.
He climbed as high as the 22nd floor before officers grabbed him.
Police identified him as a 20-year-old man from Virginia, and said he was in hospital for evaluation.
A day before the ascent, the climber had posted a video on YouTube titled “Message to Mr Trump (why I climbed your tower)”, police said.
He posted the video under the name Leven Thumps, which is a character in a series of children’s fantasy novels by the writer Obert Skye.
“I am an independent researcher seeking a private audience with you to discuss an important matter. I guarantee that it’s in your interest to honour this request,” he wrote.
“Believe me, if my purpose was not significant, I would not risk my life pursuing it. The reason I climbed your tower is to get your attention.”
Police monitored the climb, smashing windows and breaking through a ventilation duct in an attempt to block his progress up the skyscraper that is the home and headquarters of Republican presidential nominee Trump.
They grabbed him and hauled him into the building through a window, two hours after he started.
Television footage showed the shaggy-haired man dressed in shorts and a T-shirt.
He was named “the human fly” on social media.