The finds were made by a team carrying out archaeological excavations on behalf of the Highways Agent as part of preparation for the scheme.
Flints and burnt hazlenuts are just some of the evidence pointing to hunter-gatherer prehistoric tribes living in the area.
The archaeological findings date from the Mesolithic to the Bronze Age periods - around 5000 to 2000 BC.
The team working on the excavations around the new link road have also discovered Roman pottery and tiles that are stamped to show they were made for the 20th Roman Legion based in Chester around 167 AD.
It was already known that the site had some archeological importance. Excavations in 1993 ahead of the construction of the adjacent A5300 uncovered part of a Roman farm. Other finds hinted at prehistoric activity in the area - now that has been confirmed
HA project manager Gary Hilton said: "The Highways Agency takes its responsibility for our heritage very seriously and we are delighted to have found this window into the past. Lots of people are very excited by what has been discovered here.”
Now the HA is inviting to people to see some of the rare finds that have been discovered, which include 2000-year-old Roman pottery. Open days will take place on Friday 1 and Saturday 2 February.
Mr Hilton said: “We are obviously keen to show off these discoveries and this is why we have decided to hold the open days. We will be turning this important construction site into a museum for the day, before the artefacts are handed over to the experts who will be able to preserve them for future generations.”