I read a hell of a lot so I would suggest a book on any subject you may be interested in.
Book prices on Amazon start at about 99 cents and if you are a Prime member and have a Kindle, you can make a purchase and start reading immediately.
Here are a few suggestions:
Charlatan: America's Most Dangerous Huckster, the Man Who Pursued Him, and the Age of Flimflam.
Or one or all of the following which previous GetBiggers have mentioned.
Genghis Khan and the Making of the Modern World by Jack Weatherford
1177 B.C.: The Year Civilization Collapsed by Eric H. Cline
Tesla: Inventor of the Electrical Age by W. Bernard Carlson
(Some are in Audio format)
My best reads have been:
Nicholas and Alexandria (Russia's last Czar)
Dancing Wu Li Masters (an elementary attempt to explain Quantum Mechanics). I think that you can still download this for free in PDF Format.
It's well worth reading!