The skull is believed to be that of a woman in her 50s
A rare 2,000-year-old Roman skull has been returned to the cave beneath the Yorkshire Dales where it was discovered by divers in 1996.
Archaeologists were called in after cave divers unearthed human bones in what is believed to be one of the most important cave discoveries ever made.
The skull dates to the 2nd Century and is that of a local woman in her 50s.
It was stored at Sheffield University for carbon-dating and recently returned to the cave, which has now been sealed.
There are other human remains in the cave which date back to the Bronze Age - more than 1,000 years before Roman Britain. Animal remains, including horses and dogs, have also been excavated.
Cave burials from this period are rare so this site is considered an archaeological treasure trove.
Experts believe the cave could have been a tomb, but that some of the deaths may have been through sacrificial ceremonies.
Tom Lord, research fellow at Lancaster University, has studied ancient bones in caves for more than 20 years and believes there is more to be unearthed in the cave.
The team block the cave up so the skull remains in peace
Mr Lord calls the cave an "ancient time capsule" because of the many different remains inside. He believes the cave was considered a sacred place for centuries because of its supposed entrance to the underworld.
He also referred to the cave as an "ancient crime scene" because it may have been the scene of forced sacrifices.
Ancient bodies have also been discovered in what are thought to be sacrificial caves in East Yorkshire.
The skulls excavated from East Yorkshire show the bodies suffered blows to the head, and were therefore sacrificed by force.
Unfortunately the recently-returned skull is only a partial skull and there are not enough remains to determine how the Roman woman died.
One theory is that she may have been a high-born figure from the local area who voluntarily sacrificed herself, believing she would enter the underworld.
Other factors could, however, point to the woman wanting to escape Roman hardship.
The skull has been laid to rest under a shelf in the cave where it is hoped it will remain undisturbed.
Mr Lord said that if archaeologists chose to reinvestigate the cave in the future, much more could be unravelled.
For now though, the cave has been shut, disguised with earth and rock and sealed completely.
Inside Out, BBC1, Friday 11 April at 1930 BST