Mont Blanc massif
... that to hike round the Mont Blanc massif in the Alps is a 170-kilometre (110 mi) trip, usually taking 11 days, but top athletes run round the Tour du Mont Blanc circuit in just 21 hours?
... that to hike round the <b id="mwAjA"><a href="./Mont_Blanc_massif" id="mwAjE" rel="mw:WikiLink" title="Mont Blanc massif">Mont Blanc massif</a></b> in the <a href="./Alps" id="mwAjI" rel="mw:WikiLink" title="Alps">Alps</a> is a <span about="#mwt32" data-mw='{"parts":[{"template":{"target":{"wt":"convert","href":"./Template:Convert"},"params":{"1":{"wt":"170"},"2":{"wt":"km"},"adj":{"wt":"on"}},"i":0}}]}' id="mwAjM" typeof="mw:Transclusion">170-kilometre (110</span><span about="#mwt32" typeof="mw:Entity"> </span><span about="#mwt32">mi)</span> trip, usually taking 11 days, but top athletes run round the <a href="./Tour_du_Mont_Blanc" id="mwAjQ" rel="mw:WikiLink" title="Tour du Mont Blanc">Tour du Mont Blanc</a> circuit in just 21 hours?