Although the public announcement only took place in 1994, archaeologist Nelson Rebanda, who accompanied the construction of the Côa dam, identified the first engraved rock (1 of Canada do Inferno) in late 1991. This is not to say that people of the region, especially the shepherds or the millers who worked on the banks of the river precisely in the zone of Canada do Inferno had not seen the engravings before. However, they lacked the information to ascertain the great antiquity of these figures. The discovery soon provoked great discussion as the construction of the dam would cause the submersal of the Côa Valley rock art.
In 1996, the Portuguese government, in view of the experts’ opinion regarding the artistic and scientific importance of the Côa rock art, and the great number of sites that were discovered since 1991, decided to abandon the construction of the dam. At the same time, the Côa Valley Archaeological Park was created to protect and show to the public the rock art ensemble. The Côa Valley is the largest open-air rock art collection from the Paleolithic known today.
Recognition by UNESCO of the Côa Valley rock art as World Heritage on December 2, 1998, was the culmination of a process that would indelibly mark Portuguese Rock Art, Archeology and Cultural Heritage. In 2010, UNESCO also listed the nearby Paleolithic rock art of Siega Verde (Ciudad Rodrigo, Spain) as an extension of the Côa.