This photo was snapped by Walter Callens at Gobustan (sometimes written as "Quobustan") in Azerbaijan.

His description:

Settled since the 8th millennium BC, the area contains thousands of rock engravings spread over 100 square km depicting hunting scenes, people, ships, constellations, animals, etc. Qobustan's consecration in the world stage arrived in 2007, when UNESCO included the 'Qobustan Rock Art Cultural Landscape' in the World Heritage list.

The oldest petroglyphs date from the 12th century BC. Later, the European invaders also left their marks: inscriptions left by Alexander the Great's cohorts in the 4th century BC and 2,000-year-old graffiti written by Trajan's Roman legionnaires!

Learn more about this remarkable historical site at UNESCO

And just in case you're wondering, a petroglyph is a picture or symbol engraved on a rock surface; a hieroglyph is a pictorial character used as a writing symbol, particularly in Ancient Egypt. Where their shared suffix -glyph derives from the Greek for "writing," petro- means "rock" while hiero- translates to "sacred." 

Photo credit: Walter Callens / Flickr (click for higher res)