From 10am – 4pm, visitors will be able to see inside the tower Mill on Mill Road, talk to experts about milling and watch a short video about the history of Ellis Mill.
The Mill, built in 1798, is the last of nine windmills that stood along the ridge in the city.
Steve Dunk from Lincolnshire County Council comments:
"We're absolutely delighted to be opening the Mill once again. We're opening the ground floor so people can see the fascinating inner workings.
"We've also have our knowledgeable volunteers on hand to talk about the processes and the history of the building.
"Its set to be a brilliant weekend – so come along and find out more."
Lincoln Castle, Museum of Lincolnshire Life, the Collection will also be open for visitors during the Heritage weekend.
Entry is free. No booking required.