Here's the summary from Wikipedia. What year would you guess the project started?
This hole was dug by the Ministry of Defence of Bulgaria, who excavated an area in the center of the village during a project active from ____ to ____. A group of psychics convinced some influential military members to start an excavation. As the secret "Operation Lightbeam" commenced, the psychics changed their opinion on what to find in Tsarichina several times. They were looking "for a creature – a "yellow-haired monkey", a "Biblical personage", a "hermaphrodite extraterrestrial that would disprove Darwin's theory of evolution and would reveal humanity's extraterrestrial origins", or the hidden treasure of Tsar Samuil. After digging a 160-metre (520 ft) long tunnel at a depth of 70 metres (230 ft) without finding anything for two years, the project was abandoned