Multimedia & Literature

Audio and Video

Backmasking	Backmasking (backward masking) is a recording technique in which a sound or message is recorded backward onto a track that is meant to be played forward. Not all the messages that can be found by reversing audio are necessarily intentional.
The Bloop	The Bloop is the name given to an ultra-low frequency underwater sound detected by the U.S. National Oceanic and Atmospheric Administration several times during the summer of 1997. The source of the sound remains unknown. Because the Bloop noise originated near the location of the fictional sunken city of R'lyeh from H.P. Lovecraft's story "The Call of Cthulhu", the Bloop has been linked to Cthulhu by Lovecraft fans.
Cure for Insomnia	The world's longest movie, with a length of of 85 hours(!).
Electronic Voice Phenomenon (EVP)	Sections of recorded audio (generally within static) on which voices or other recognisable sounds are heard, which were not audible when the audio was originally recorded.
The Hum	A generic name for a series of phenomena involving a persistent and invasive low-frequency humming noise not audible to all people. It is most often described as sounding somewhat like a distant idling diesel engine, but is typically difficult to detect with microphones, and its source and nature are hard to localize.
Infrasound	An undetectable (to human ears!) sound that can induce feelings of awe and fear, and falsely seem supernatural. It can also resonate the human eyeball, causing blobs and vague figures to appear.
Number Stations	Radio broadcasts of unexplained purpose - presumed to be military - with unusual transmissions. Different stations are all over the world, and some have been operating continuously for decades.
Radio Station UVB-76	Russian shotwave station that transmits a buzz tone 23:10 hours per day since the early 1980s. Only three voice messages have been observed during this time.

Literature

Dante's Inferno	Written by Dante Alighieri between 1308 and his death in 1321, is widely considered the central epic poem of Italian literature, and is seen as one of the greatest works of world literature.
Futility, or the Wreck of the Titan	A novella which describes a story very similar to that of the sinking of the Titanic, except that it was published fourteen years before the accident occurred.
Voynich Manuscript	The Voynich manuscript is an illustrated book written in an unknown and as-yet undeciphered text. It is thought to have been written around the 15th century. The author and script of the manuscript remain unknown - even the purpose is largely a mystery.

Images

The Hands Resist Him	A painting with an (admittedly false) story of a haunting. It was pretty popular on the internet back around 2000.
Piri Reis map	A 16th century map, most noteworthy because it appears to show Antarctica which at the time was not even known to definitely exist.

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