The 2012 Tour De France has been brought forward by a week due to the London 2012 Olympics.
The race now will start in Liege with a 6.1km prologue from Liege to Centre Ville (Boulevard d'Avroy) on Saturday June 30th 2012, followed by the 180km first stage from Centre Ville (Boulevard d'Avroy) to Seraing the next day.
The decision means that the riders involved will have nearly a week to get to London for the mens road race.
Although considering that the Olympic Road Race which takes in Richmond Park and parts of Surrey, where you will be able to watch the riders for free, comes in between the Tour De France and one of the two main grand races the Vuelta de Espana, priorities for some of the riders who are paid by their teams not their countries, may lie elsewhere