Archaeologists are to excavate a car park behind a former council building before the site is redeveloped.
The investigations at North Quay, Weymouth, are being conducted as part of permission to demolish the former Weymouth and Portland council building.
The dig by Context One Heritage and Archaeology will begin on 18 September and is expected to take about 13 weeks.
It was the site of the Battle of Weymouth in 1645 during the first English Civil War.
It followed a royalist plot to return the ports of Weymouth and Melcombe to King Charles I.
The car park has been closed in preparation and will reopen following the demolition in spring 2024.
Dorset Council has appointed the same archaeology team that led previous digs at North Quay and a former bowling alley in St Nicholas Street.
Assets and property councillor Andrew Parry said: “The explorations that Context One and the local volunteers uncovered at North Quay in 2021, and across the harbour at the MFA Weymouth Bowl site in 2022, were beyond anything we thought might be unearthed.
“Having the chance to peer beneath the tarmac once again, to a Weymouth hundreds of years old, is a very exciting prospect.
“There is such a rich and unique history right under our feet that never fails to amaze.”
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