It's officially called Up At The O2, but everyone's going to call it "That walkway on top of the Dome". We gave it a try at the weekend. Here's how we got on.
We start at "Base Camp". It's a small prep room that seats about 30 people, the maximum group size. A cheesy introduction video sets the scene via a hammy Brit explorer-type who seriously needs to lay off the caffeine. More soberly, three sides of A4 outline the various dos and don'ts of climbing over a world-famous landmark. We sign on the dotted line.
Next comes the locker room, where we receive protective overalls and a safety harness, and stow bags in lockers. The 30-minute briefing and full-on jumpsuit feel like health and safety overkill at this stage, but we soon revise such thoughts. There's a bit of faffage getting everyone kitted-up, and a worrying lapse of technology when our guide can't unlock the back door, but we'll put these down to first-week teething problems. Everything else goes smoothly.
The ascent starts three storeys up on a metal tower. We attach our individual safety lines to the guide rail and begin our climb. And climb is the right word. The walkway slopes at 30 degrees and, while most people could take such a gradient without too much trouble, the strong cross winds, bouncy surface and all-too-obvious drop conspire. The rail cable and safety line become our new best friends.
We inch our way up. The temptation is to press on ahead, but the group must be kept together. The first section is the steepest but, as if to compensate, the winds pick up as the walkway flattens out near the top. The attraction will stay open at anything up to 40mph. We're only at half that, and it feels decidedly challenging.
And then we reach the summit — the O2 nipple, as we're non-officially dubbing it. This circular haven is enclosed by rails. No need for safety ropes here. Our platoon spreads out. We are finally able to deploy our cameras and phones. A few people simply stand and admire the view. Most, however, are grappling with Twitpic, Instagram and Facebook. It would seem perverse not to, given that we're on top of the world's biggest advert for mobile phones.
All too quickly, it's time to descend. The down-trail is trickier, with a longer steep section to ground level. At no time does it feel unsafe. Our guide is reassuring and professional, if a little overfond of the word "guys". We reach terra firma after about an hour on the structure.
Unless you work for a big construction company or are one of those urban explorers who enjoy covertly scaling tall buildings, you've never done anything quite like this before. It's not scary, and it's not that difficult if you're of average fitness. It is exhilarating, and shows what a spectacular building the Dome really is. Up At The O2 emphatically confirms the venue's remarkable rehabilitation from a derided white elephant to one of London's most successful buildings.
Now, let's see them open one of these over St Paul's.
Up At The O2 costs £22 for adults and children, and can be booked here. You need to be at least 10 years old, and 1.2 metres high.