The Paralympic Torch Relay got under way on Wednesday when flames were lit at the summits of the highest peaks in England, Northern Ireland, Scotland and Wales.
Flame celebrations began in London's Trafalgar Square on Friday and will move on to Belfast, Edinburgh and Cardiff over the long weekend.
In each of the cities there will be a ceremonial cauldron lighting where the national flame will be transferred from a miner's lantern to a torch, and then from a torch to the cauldron.
Thirty-eight communities across the UK will also host their own flame celebrations, sending an ambassador to one of the capital cities to collect part of the national flame.
Claire Lomas, who walked the 2012 London Marathon in a pioneering robotic suit to raise money for spinal research, lit a ceremonial cauldron in Trafalgar Square.
During the day the flame will also visit the Royal Opera House, the Notting Hill Carnival and the Houses of Parliament.
The Northern Irish flame will light a ceremonial cauldron outside Stormont in Belfast, followed by various community visits and a flame festival in the evening outside City Hall.
The flame festival will include a lantern procession at Meadowbank Sports Centre.
The Welsh flame will light a ceremonial cauldron outside City Hall in Cardiff.
There will be visits to Rockwood Hospital, House of Sport Coaching Academy and the Live Site, and the flame festival will include a lantern procession in Roald Dahl Plass.
The four national flames will arrive at Stoke Mandeville, the spiritual home of the Paralympic movement, where they will be united in a special ceremony to create the London 2012 Paralympic Flame.
The flame will then embark on a 24-hour overnight relay.
The flame will be carried 92 miles by 580 torchbearers, working in teams of five.
They were selected through public nomination campaigns run by BT, Lloyds TSB and Sainsbury's, as well as the British Paralympic Association, the International Paralympic Committee and other London 2012 sponsors.
The torchbearers will include former boxer Michael Watson and Dame Tanni Grey Thompson.
The route will take the flame through communities in Buckinghamshire and Hertfordshire, before visiting all six host boroughs and a number of London landmarks, including the famous Abbey Road crossing, Lord's Cricket Ground, London Zoo, Piccadilly Circus and Tower Bridge.
It will eventually arrive at the Olympic Stadium in Stratford for the official opening of the Games.
For more details of the flame relay and ceremonies, visit the London 2012 website.