Plymouth City Museum and Art Gallery is closing its doors on Saturday for almost six months.
The museum will fully reopen in September
Thousands of pounds of work is being carried out to create three new galleries, with a revamped shop, cafe area and foyer.
The money comes from a £750,000 grant from the Heritage Lottery Fund along with money from Renaissance in the Regions and the Department for Culture.
The first floor will re-open in May and the ground floor in September 2008.