Penascosa Petroglyph – Vila Nova de Foz C?a, Portugal - Atlas Obscura
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Penascosa Petroglyph

Vila Nova de Foz C?a, Portugal

These rock drawings in the C?a Valley also create an ancient optical illusion.  


The little valley of the C?a River in northern Portugal is home to an amazing collection of Paleolithic rock art. Thousands of figures of horses, bovines, and other animals, along with human and abstract figures were created beginning perhaps 22,000 years ago. The tradition continued throughout the Stone Age and into the Bronze Age.

One particularly imaginative engraving is quite fascinating. It’s not the biggest or the most complicated design, nor the most complete or detailed in the valley.?At the Penascosa site, one of three open to the public, a three-headed horse puts on a show for lucky viewers.

Many of the animal carvings tend to overlap one another, this one in particular creates a unique illusion. When the flickering light of a fire illuminates the rock, the horse appears to move its head. Experiments trying to recreate this effect with a flashlight are not always successful.?

The Prehistoric Rock-Art Sites in the C?a Valley were designated a World Heritage Site by UNESCO in 1998. The C?a Museum is a beautiful modernist building blended into a hilltop that overlooks the confluence of the C?a and Douro Rivers.?

Know Before You Go

Visiting the sites requires booking a guided tour through the museum, or perhaps through private licensed guides.