Spalding Gentlemen’s Society Museum in Broad Street is opening its doors to the public on Sunday free of charge.
There are two tours, one at 1.15pm and the next at 2.45pm.
It is the first experimental Sunday afternoon opening to see what demand there is for informal museum visits.
Chairman of council Nick Caswell said: “We are doing this because we feel we can reach the public and get more people through the door.”
Visitors will see thousands of items of local and national interest.