Towering 114.5 metres above central London - it's no feat for the faint hearted.
But now two friends are preparing for the challenge of a lifetime as we celebrate our 30th birthdays.
Charlotte Leng and Rebecca Pearson have signed up to take on Britain's highest freefall abseil - plummeting from the top of the ArcelorMittal Orbit in the 2012 Olympic and Paralympic park.
But before we face our fears for the daring drop on the 18th May (seven days after Bex's big three-oh) we hope to raise £1,000 to transform the lives of people with disabilities.
The cash will go to Canine Partners, where we work as part of the marketing team, and it will help pay to train life-changing assistance dogs.
The dogs have skills like no other and can open doors, undress a person and even help use a washing machine.
These tasks boost their disabled partners' independence and confidence in ways words cannot describe.
Through our work at the charity we have met so many people who are supported by these amazing dogs and seen first hand just how much difference they make.
That's why we're asking you to dig deep as we take the plunge.
Every pound will help train a hound.

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