The current Open Air Modern Art Museum in Hecho came into being as a result of the celebration of the International Sculpture and Art Symposium from 1975 to 1984, through the initiative of Pedro Tramullas and with the invaluable help of Romualdo Borruel, mayor of Hecho at the time and whose vision and cooperation were decisive for the celebration of this event at a time in which Spain was taking its first tentative steps in a new democracy. For a mountain village like Hecho, the symposium and its subsequent editions became a social and cultural occasion which through art transmitted new experiences and emotions to its inhabitants. During the Symposium, parallel cultural events such as concerts, plays, meetings, debates, conferences and open air pottery and engraving workshops took place for the general public, alongside the creation of the sculptures by each individual artist.

Today the Museum exhibits sculptures by the participating artists, including Joshy Stieber, Claude Cunda, Ricardo Calero and Vicente Villarrocha in its indoor exhibition space and Tetsuo Arada, Bernard Johner, Patrick Lesné, Toshitsugo Yamahata and Pedro Tramullas himself in an outdoor exhibition area, which together make up a collection of singular cultural value.