A 2,000-year-old computer made of bronze.
In 1901, sponge divers pulled a corroded bronze device from a shipwreck off the Greek island of Antikythera. Built in the 2nd or 1st century BC, it used at least 30 gears to calculate positions of the Sun and Moon, eclipses, and the four-year cycle of the Olympic Games. Europe didn't build gearing this complex again for about 1,400 years.
Useful: When an ancient culture seems 'primitive' to you, check whether its tools simply didn't survive.
Source: en.wikipedia.org