Thanks to Reuben Hutton for recommending the following video. The 'Tor des Geants', or Tour of Giants, is a multi-day foot race over the Italian Alps, starting in the town of Courmayeur (where I was earlier this year skiing) and finishing, after a loop of climbs and descents, in the same place. It started in 2010 and looks to be one of the toughest races there is - reserved for the fit and determined! For more: http://www.tordesgeants.it.