Two people climbed to the very top of the Empire State Building on Wednesday and unfurled a banner bearing a peace message.
The banner read, "When the power of love beats the love of power the world knows peace," a quote commonly attributed to Jimi Hendrix, who died in 1970.
A spokesman for the building's management told dpa that the action, which took place about 440 metres above the city, had not been authorized.
With the assistance of police the situation was quickly brought under control and posed no danger to people inside the skyscraper, he said.
Police said the two individuals were temporarily detained.
According to US media reports, the pair are Russian urban climbers Angela Nikolau and Ivan Beerkus who have previously been featured in a documentary film.
Video captured by a news helicopter showed one of the climbers dropping to one knee after the pair descended to a platform below the structure supporting the building's antenna, in what seemed to be a marriage proposal.
