The concept of bouldering circuits comes from the world famous sandstone bouldering area Fontainebleau just South of Paris, France.The first painted circuit (small colored arrows and numbers are painted onto the rock to signify each bloc) was created in 1947 by Fred Bernick in the Cuvier Rempart area, followed by routes at Les Gorges d'Apremont painted by Pierre Mercier in 1952. The standardization of route color by difficulty (Yellow = PD, Orange = AD, Blue = D, Red = TD, Black = ED, White = ED+) dates back to the 1980s.