The tunnel in Guizhou Province, China, became the focus of investigation after hundreds of people reported going back in time once they exited the 400-metre structure.
Most people reported gaining an hour in time after continuing their drive outside the tunnel, as their mobile phones had gone back exactly 60 minutes.
The phenomena became so well known that one journalist working for the Gui Yang Evening News decided to carry out an experiment.
He drove through the tunnel - an about five minute journey - ten times, and reported gaining an hour on eight of the trips.
With no apparent explanation, and the time gain baffling so many people, conspiracies and theories have abounded online, including everything from real time travel to alien abductions.
One person posted on neowin.net: "Clearly the drivers have missing time, and were probed by aliens."
I want to go forward in time. To read more, click here.