This is the first known adult skull of a Neanderthal (Homo neanderthalensis) ever discovered.
It was found in a quarry in Gibraltar in 1848 - eight years before a similar skull in Germany's Neander Valley was discovered, and sixteen years before that skull was named as an extinct human species separate from us.
This skull's significance was therefore not understood at the time, but after the Neander Valley discovery in 1856, it was re-examined and recognised as belonging to the same extinct human species.
Since then, scientists have explored Gibraltar further and found evidence that Neanderthals inhabited this area for tens of thousands of years, likely due to the mild and stable climate. This region may have been one of the last places in which Neanderthals survived.