"The Eternal Savage" by Edgar Rice Burroughs is a fantasy-adventure novel first published serially in 1914-1915. A cliff-dwelling warrior from 100,000 years ago is magically transported to the present, where he encounters Victoria Custer—the reincarnation of his lost love. Together, they are swept back to the Stone Age in an African setting that weaves together characters from Burroughs's other works, including Tarzan and the protagonist of "The Mad King." (This is an automatically generated summary.)
These books are free to read. Each is in the public domain in the United States; check your own country's rules before you copy or share one.
