Activists for Greenpeace are climbing to the top of Shard building in London on Thursday in a protest over drilling in the Artic.
They chose the building because it is owned by Shell Oil, and it is also the tallest building in Britain.
During the climb, the activists tweeted messages and photographs from their head-mounted cameras.
The activists were six women, who have all reached the top. Live streaming was broadcast on the Greenpeace #iceclimb site.
It started around 4 a.m. and went on for a few hours. It is not known if the women were arrested when they finished climbing.
The British Mountaineering Council recognized the climb and noted that it was developed in 2013 by one team. They offered a humorous guide on their site for the climb.
Their site said, "A photogenic and very public crag. Offers an adventurous and arresting challenge for climbers who can manage the delicate approach.
Approach at night, wearing dark clothes and in an unmarked van. The initial tricky pitch to the roof of London Road station gains a spacious belay ledge. Initial care must be taken to avoid disturbing any nearby policemen. However, once on the 72-storey route, climbers can relax and live webcast, tweet, and unfurl banners."