It took between 14 and 20 years
It is estimated that construction took between 14 and 20 years, around 2560 BC.
Modern estimates put it at 14-20 years (c.2589-69BC) According to the ancient Greek historian Herodotus who lived c.450BC, 100,000 men were employed in its construction. Just think the pyramid was...
20 years
Around fifty. It took thousands of men to build it.