800 athletes spread over 21 floats will leave Mansion House at 1.30pm, then travel along Queen Victoria Street, Cannon Street, Ludgate Hill, Fleet Street and The Strand. They'll then pass Trafalgar Square, where a big screen at the base of Nelson's Column will have live commentary.
That part of the route is a free-for-all; if you want to watch you're advised to get there early, pick your spot and stay there. After Trafalgar Square the parade will pass through Admiralty Arch towards the Queen Victoria Memorial. This will be invite only, partly because there'll still be a load of equipment left over from the Paralympic marathon, partly because organisers want to make sure Games Makers, emergency support workers, the military and Team GB coaches and staff get a chance to be part of the celebration.
In typical florid style, Boris Johnson said:
In the ancient world crowds would line the streets to welcome their triumphant Olympians home, where they would be ecstatically venerated and their victories chronicled for the ages, with names like Leonidas of Rhodes and Milo of Kroton reverberating through history. But no sporting heroes will have been more lauded, no achievements more celebrated, and no nation more passionately proud than at the Our Greatest Team Parade, which will sweep through central London in a glorious miasma of colour, noise and excitement.
Alternatively, the whole parade will be broadcast on TV. You can read more details on the Mayor of London Presents website.