John D. Rockefeller was the richest man in history(actually richest self-made man in history, the actual richest man being Mansa Musa). In today's money his net worth will be about $400 Billions. This video was inspired by the book Titan The life of John D. Rockefeller Sr. by Ron Chernow and also the movie The men who built America.
John D. Rockefeller built his massive wealth through his company Standard Oil which controlled 90% of the oil production of the world. In 1911, the company was dismantled by the US government and today Exxon Mobil, BP and Chevron are all descendents of Standard Oil.