Telescopes as we know them today trace their origins back to the Enlightenment. The earliest such devices emerged about 400 years ago. But humankind has fashioned environments for stargazing for far longer than that. Scholars have long speculated about the astronomical orientation of the Pyramids at Giza, for instance, and the possibility that Stonehenge was built to be a celestial observatory. Now, there’s evidence of ancient telescopic structures that date back even farther, to about 6,000 years ago. Astronomers are exploring ancient tombs in Portugal that they believe may have been used by prehistoric humans to enhance specific views of the night skies. Researchers are focusing on the alignment of the stars with megalithic tombs—stone structures known as dolmens that feature long narrow entrances that act as apertures, essentially zooming in on stars and planets that wouldn’t always be visible from the outside.
http://www.theatlantic.com/technology/archive/2016/06/oldest-telescope/489362/
