Join Barclays, UNICEF and Heart Radio's Have a Heart - along with some very familiar faces - to walk through the night to build a brighter future for vulnerable children in London and Rwanda.
Participants include Charley Boorman, Dwain Chambers, Tina O'Brien, Sinitta, Ali Bastian, Kristina Rihanoff and Heart FM's Harriet Scott.
The route starts and finishes at Potters Fields Park and heads through the City to Trafalgar Square, returning to the South Bank at the Golden Jubilee Bridges.
You can still take part in the event by signing up on the night.
Simply go to the registration desk at Potters Fields Park between 6pm and 7pm.
A mini-festival will take place close to the start line featuring live entertainment and food and drink stalls.
Related website: www.barclays-step.com