The Stone was discovered on July 19, 1799.
It held the key to deciphering the language of the ancient Egyptians by translating a passage of hieroglyphics into Greek.
Within a few years of being found in Egypt, the stone was shipped off to London where it remains to this day. Its caretakers spread wax across the surface to prevent it from being worn down by all the people who ran their fingers across the inscriptions.
The darkly colored wax led to the mistaken belief that the stone was basalt. Its true composition was revealed only after a cleaning in 1999.