Trenches will be dug at North Place car park as part of the survey
Archaeologists are to start digging at North Place and Portland Street car parks in Cheltenham.
Eight evaluation trenches, each 30m (98ft) long by 1.85m (6ft) wide, will be dug in three separate phases over the course of three weeks, depending on any finds.
The dig is part of preparation work ahead of potential development at the sites.
The car parks will remain open while the work is carried out.
Jeremy Williamson, managing director of the Cheltenham Development Task Force, said: ''It is fundamental that we understand the site and establish the constraints before we consider marketing the sites for development.
"An understanding of the archaeology will allow any proposals in the future to respect any sensitive areas which can be protected where necessary by the type of foundations deployed, or even remaining as open land which does not disturb the archaeology.
"If there is something there then the most important thing is we can develop strategies to protect it, not build over it, or design solutions such as raft foundations to protect it long term in the future."
The first trench will be started on Monday, 11 October.
Whilst sections of the car parks will be cordoned off, they will still be open as usual for members of the public to use.
The archaeological survey follows a desk based analysis carried out by Gloucestershire County Archaeology Services to determine the potential for remains in this part of town.
The analysis concluded that some parts of the site have had little disturbance over the last century and therefore have potential for remains, whilst other parts are likely to have been destroyed by cellars from previous buildings now long gone.
The focus for the survey will be on those areas identified with the greatest opportunity for intact remains.