Analysis is to begin on a number of ancient human remains discovered by developers in Preston city centre.
It is believed the graves may have come from a medieval friary
The bones - unearthed at Marsh Lane, near its junction with Ladywell Street - are believed to be from a medieval burial ground.
A total of 30 graves were uncovered in February, with around 12 containing virtually complete skeletal remains.
Experts from Oxford Archaeology North hope to carry out tests to establish a precise age for the bones.
They would use dendrochronology to count the tree rings in the oak which made the coffins and, by comparing them with a database, will be able to pinpoint when the trees were felled.
Although this does not help establish when the coffins were made, it will give experts an indication of the era.
This, coupled with radiocarbon dating of the skeletons, will enable them to date the burials within 50 to 100 years.
It is believed the graves may have come from a medieval friary dedicated to St Clare which was located in Preston from 1260 to 1539.
Medieval glass and floor tiles thought to be up to 700 years old were also discovered at the site which was sold on as a private residence in 1539, with part of it turned into a jail in 1680.
Stephen Rowland, a project manager at Oxford Archaeology North, said: "In terms of historical interest, this find in Preston is unprecedented.
"Almost nothing is known about the Preston friary apart from when it was established and disbanded.
"It was located on old maps but these were never particularly accurate.
"There has never been any significant archaeological evidence about the friary until now."
The skeletons will be re-buried once the analysis has been carried out.