More than 100,000 protesters are to descend on central London to demand a vote on the final Brexit deal.
Here, we explain when and where the march will take place.
Demonstrators will assemble from midday north of the Hilton Hotel on Park Lane, before marching along the eastern edge of Hyde Park.
Protesters will then turn onto Piccadilly, proceeding on to Trafalgar Square via St James Street and Pall Mall.
Crowds will head down Whitehall, past Downing Street, before finally gathering in Parliament Square.
Here, from 2pm, the crowds will hear speeches from household names such as chef Delia Smith, Dragons' Den star Deborah Meaden and London mayor Sadiq Khan.
Some 150 coaches will bring activists to the march from across the country, with a string of coaches sponsored by stars including football manager Alan Pardew, actor Natascha McElhone, writer Armando Iannucci, ex-footballer Jamie Carragher and singer Olly Alexander.
Numbers are expected to far exceed the last march in June when around 100,000 turned out, and organisers have extended the route to accommodate larger crowds.