The two most famous cities near Mont Blanc are Chamonix, Haute-Savoie, France and Courmayeur, Valle d'Aosta, Italy. Begun in 1957 and completed in 1965, the 11.6 kilometer (7.25 mile) Mont Blanc Tunnel runs beneath the mountain between these two cities. It is one of the major trans-Alpine transport routes particularly for Italy who rely on the tunnel for shipping as much as one-third of their freight to northern Europe.
In 1999, 39 people died when a fire erupted in the 8.6 meter wide tunnel when a Belgian transport truck carrying flour and margarine caught fire. The fire, reaching temperatures of 1,000° Celsius, trapped around 40 vehicles in dense and poisonous smoke. As a result, the tunnel was closed for three years while numerous safety features were installed.