Because it was a famous french road who allows to go from Paris to the French Riviera ( Côte d'Azur ). It's the symbol of freedom, holidays and sun. In July or August, you could see ( from the early 30's till the end of the 60's ) a lot of cars - 2CV, Traction, Buick, Simca, Peugeot, Renault, Mercedes, Triumph...) with family and luggage "going down" ( that means going to the south ) to the sun... But, because of the famous Nationale 7's traffic jams during the 60's, a highway has been made... Nostalgia, nostalgia...
Nationale7 is a team of two french friends, Eric ( his own gallery : Emy10 on RR ) and Alain ( his own gallery : 3DClassics on RR ).