The discovery of "nationally important" bronze age burial mounds on the edge of Bicester has prompted a housing developer to change its plans.
Archaeologists uncovered the two mounds buried beneath land between Bicester and Chesterton, which is earmarked for 1,585 houses.
The discovery has forced Countryside Properties to draw up new plans for the site, which it submitted to Cherwell District Council last week.
Experts dug 134 trenches between July and September and found archaeological remains in 41 of them.
As well as the burial mounds, which could be up to 5,500 years old, they found a bronze age palstave (an axe head), an iron age settlement with a possible hearth, a Roman settlement and quarries and what is believed to be a saxon ditch.
Experts from Wessex Archaeology have recommended the burial mounds, which measure 32m and 21m across, be protected by a 50m no-build buffer zone.
Council planning officer Jenny Barker said developers had redrawn their plans so the mounds would be beneath the playing field of one of the proposed primary schools. She added the secondary school and the health village had also been moved.
She said: "The problem with the masterplan is once you change one thing, you have to change other things to support that."
She said the decision on the planning application, which was submitted in May, had been delayed pending the results of the archaeological survey.
But she added the findings should not cause any further delays and said the application could be still decided at December's planning committee meeting.
She said: "These mounds have been identified as significant and, in fact, significant enough that they should not be disturbed."
In its report, Countryside Properties said: "The intention is to impose a 50m buffer around these two sites to ensure no infrastructure works take place that would damage these remains of national importance.
"It is recommended that provisions are implemented to ensure that archaeology has a primary consideration in future engineering and management plans for these proposals."
In their report, experts from Wessex Archaeology said: "All of the archaeological evidence uncovered to date indicates the utilisation of this site for several thousand years."
Countryside Properties spokesman Steve Price said: "There are quite a lot of changes. A lot of the amendments are to overcome or answer some of the concerns about the proposal from the public - the result of feedback from various consultations."