The origin of the festivity is completly unknown.

The inhabitants of Isil can’t explain as to when or why this festivity started; they say that it´s a tradition that has always been celebrated and there are no official documents or diaries that explain its origins. In fact, cultural experts are also somewhat mystified by the exact beginnings of the Falles de Isil.

The tradition of lighting a fire in celebration of St. John is a festivity that not only is active in Isil, but all over the Catalán territories. The celebration of the summer solstice, has had since pre-historic times such a complex ritual that today we still can´t grasp it and there are many and diverse theories as to its meanings and origins. Folklorists, ethnologists and anthropologists have all studied one of the most compelling theories which relates the celebration of the fire with fasting and cleansing; and those periods of the year which have an exceptional and sacred character where fire, herbs or water gain significance. One of these periods of significance is the night.

On the 7th of June 1991 when Falles were declared a “National Interest and Traditional Festival”

In June 2010, the Government granted the celebration the category of “Heritage National Festivity”

In December 2015, together with 63 villages of the Pyrenees of Catalonia, Aragon, France and Andorra, Les Falles Isil were declared Intangible Cultural Heritage of Humanity by UNESCO in the nomination "Les festes del foc del solstici d'estiu als Pirineus".