This extensive art gallery provides us with a record of the Neolithic period and the Iron Age, and then transports us in one fell swoop across two thousand years of history to settle in the Modern Era with its religious representations, names, dates and even, only a few decades ago, some figures drawn by the children of a local miller.Almost all the motifs are engraved in the rock, presenting us with themes, techniques and conventions common to those other contemporary works in Western Europe which were discovered in the nineteenth century hidden in the French-Basque caves and by the turn of the century were already referred to as great art.
The very size of this area was sufficient to dictate the creation of Portugal's first archaeological park, which since December 2, 1998 has been included in the list of monuments classified by UNESCO World Heritage.
Such classification was the result of a sudden and radical change in government policy, beginning in October 1995 with the decision to suspend the already well advanced project for the building of dam designed to promote the first phase of hydroelectric development in the River Coa.
The subsequent simultaneous creation of the Coa Valley Archaeological Park and the National Rock Art Centre, both of which are based in Vila Nova de Foz Coa, represented the culmination of an important decision that will clearly have a crucial effect on the status of rock art, archaeology and heritage in Portugal at various levels.
The themes of the engravings are basically zoomorphic, with drawings of mountain goats, horses, aurochs (wild hulls) and deer.
Through the imposing mountains of the north-eastern region of Portugal, where in spring the almond trees are in full blossom and in autumn the vines are covered with fiery red leaves, there runs into the River Douro from the south a tributary whose name is now universally known.
This is the River Coa, whose vast valley contains many examples of a long flourishing artistic cycle.
Millennium after millennium, the rock formations that line the river banks have been converted into panels covered with thousands of engravings bequeathed to us by our ancestors' creative impulses.
Dating back to the beginning of the Upper Paleolithic Age, these open air ''panels'' bear witness to an artistic vitality and mastery that have brought us into touch with 25,000 years past time.
The first three of these species are the most common and characteristic of the earliest phases of artistic production, all of them corresponding to the large herbivores that were typical of the ecosystems of the Upper Paleolithic Age in the region.
There are also some rare engravings of fish and just one single instance of a human form, the latter occurring at the end the Upper Paleolithic Age.
As was typical of Quaternary art, signs were engraved under the form of straight lines or in zigzags, with the rocks being pecked or scratched with instruments made of quartzite or flint.