Globally, according to Thomson Reuters, GFMS has unearthed about 200,000 to 210,000 tons of gold since the dawn of humanity. If you were to merge all that gold into one large cube, it would have a size of approximately 22 x 22 x 22 meters. Although this is the most commonly used estimate, there are also other estimates that deviate by thousands or even tens of thousands of tons.
The figures vary so much because the gold is spread around the world in the form of jewelry, Gold bars, coins and decorations. There are figures of gold production from gold mines, but they do not go back to ancient times. So it's still guesswork. Due to modern production techniques, the production of gold mines has increased significantly over the past hundred years. The special thing about gold is that it does not decompose and that almost all the metal that has ever been extracted from the ground is still circulating. Due to its high value, gold is never 'thrown away' but always melted down and reused.