Archaeologists have found the remains of an ancient church at the site of St Mary's Church, Stoke Mandeville, Bucks.
The team were excavating a site which is located along the HS2 railway route when they made the discovery.
The Norman church dates back to 1080 and the remains found are thought to have once been an Anglo-Saxon church.
Beneath the church, flint walls were found that are organised into a square structure.
There has been a team of over 40 archaeologists working to unveil the Anglo-Saxon church.
Earlier this year, 3,000 medieval graves had to be moved from the church as part of HS2 planning.
They were moved to a new site and an official monument was built.
The discovery of the ruins has been deemed a "fantastic discovery".
The site is being excavated by a team from LP-Archaeology, working with HS2's contractor, Fusion JV.
Dr Rachel Wood, the lead archaeologist for Fusion JV, said: "This is a fantastic discovery that we are all very excited to excavate.
"The work undertaken at Old St Mary's is a unique archaeological opportunity to excavate a medieval parish church with over 900 years of meaning to the local community."
She went on to say that having so much of the old church still in place "including the walls and even some flooring, will provide a great deal of information about the site".
The original church was first erected after the Norman conquest, but it became derelict with some parts becoming overgrown with plants and vegetation after a new church was built in the 1800s.
Roman roof tiles have been found in the foundations of the ancient building, and it is thought that a Roman settlement existed near the church.
This means that some materials from the settlement could have been used in the building of the church.
The Anglo-Saxons invaded when the Roman's were still ruling over Great Britain.
They came from Germany and Scandinavia, and their period of control of Britain is referred to as the 'Dark Ages' because so little is known about that period.
"The discovery of a pre-Norman church in Stoke Mandeville allows us to build a clearer picture of what the landscape of Buckinghamshire would have been like over 1,000 years ago", said Helen Wass, the head of HS2 Heritage.
