Access into the mountains is facilitated by cable cars, mountain railways and mountain huts which offer overnight refuge to climbers and skiers. The long-distance Tour du Mont Blanc hiking trail circumnavigates the whole massif in an 11-day trek of . The Mont Blanc Tunnel connects the French town of Chamonix on the northern side with the Italian town of Courmayeur in the south. The high mountains have provided many opportunities for scientific research, including neutrino measurements within the tunnel and impacts of climate change on its highest slopes. Recent rises in average temperatures have led to significant glacial retreat across the massif and an awareness of the need for better environmental protection, including a call for World Heritage Site status.