Ten students have discovered what is thought to be a Viking church dating back 1,000 years.
The pupils found the remains of the medieval building on the Orkney island of Swona during a six-day trip, working with archaeologists from the Orkney Research Centre for Archaeology (Orca).
Radiocarbon samples taken by the youngsters suggest that the structure is the foundation for the church's altar.
It was discovered underneath a newer building, the Independent reports.
'The only real hint about a church being on the island is a map reference to a ruin known locally as the "Twinly Kirk", said housemaster Dan McLean, who organised the trip.
Ten students from Gordonstoun School, previously attended by King Charles, helped discover a medieval church on the island of Swona
The site is thought to date back 1,000 years and radiocarbon samples were taken for testing
'Once I had identified the site, it first appeared that the remaining church walls were of a more recent building, as they have been added to over the years.
'However, after we worked with the archaeologists to dig a test pit and clear away the weeds, we discovered a step just under the surface, leading to what would have been the church's altar.'
He described the discovery as a 'special moment' for the students to be part of.
During the fieldwork, the students, who are all from Gordonstoun, a private boarding school attended by King Charles, stayed in an abandoned house with no electricity and water from an ancient well.
Some of the pupils got involved with restoration work and helped to renovate the flooring of the old cottage they stayed in on the island.
They also had the opportunity to check out a settlement believed to be prehistoric as well as an area that could have been a Viking warning beacon.
Pupil Archie Maclean, 17, shared that the most difficult part of the trip was the 'sun and hot temperatures'.
The group would wake up at around 8am and finish for the day by 6pm.
The group stayed in an abandoned house with no electricity and water from an ancient well
Pupil Archie Maclean, 17, shared the most difficult part of the trip was the 'sun and hot temperatures'
He added: 'The archaeology dig was the most enjoyable part of the trip, being able to discover history in real time was incredible.'
Paul Clark, Orca's senior project manager, said the next step would be to analyse the samples taken from the site.
The results should reveal what sort of activity took place and allow radiocarbon dating to pinpoint exactly how old the church is.
Swona was deserted in 1974 by its last two residents, who left only a small herd of feral cattle to roam its 92 hectares.
The island is a Site of Special Scientific Interest due to its rare plants and its role as an important breeding colony for many species of seabird, including Arctic terns, puffins and razorbills.
Orcas, dolphins, pilot whales and minke whales have been spotted in the waters around it.
Vikings are believed to have been the first settlers on the island and by the mid-18th Century, Swona was home to nine families.