Discovered in 1810, they were one of the first grottos open to the public. As early as 1880, the British residents of Pau ventured into the grotto with the help of the local miller Losbats de Lestelle Bétharrram.
They were opened to the public in 1903, after several years of work by Léon Ross, an artist and one of the first photographers of the Pyrenees region. From the beginning, their huge popularity was literally "electrifying" for all : the grottos offering the added comfort of being illuminated.