The remains of a Lynn chapel could have been uncovered by workers giving Saturday Market Place a £500,000 facelift.
The county archaeologist has inspected and believes this to be part of the old charnel chapel which was demolished in 1914. Saturday Market Place is currently closed to traffic.
Under the improvement plans, the area will become a one-way system with wider pavements outside the town hall.
The car park will be reduced by 11 spaces under the proposal.