Why is gold so valuable? Because all the gold ever mined on this earth would only make a cube with sides of less than 20 metres. Yes, that is a man standing beside the lump.
Most people have heard of Fort Knox in Kentucky USA which holds vast amounts of gold for the United States - 4,578 metric which is roughly 2.5% of all the gold ever refined throughout human history. However the largest amount is in the Reserve Banks underground vault in Manhattan where there are 7,000 metric tons of gold bullion some of which is stored for foreign nations, central banks and international organizations.
Considered precious for many thousands of years, some of the oldest gold artefacts dating back as far as 4700 BCE were found in a large necropolis of around 300 graves at Varna in Bulgaria.