Tate Britain's £45m revamp
18 November 2013 Last updated at 12:32 GMT
It has taken 1,800 builders more than a year-and-a-half to complete a new-look Tate Britain.
A total of nine new galleries were opened in May, with reinforced flooring to accommodate heavy sculptures.
The second phase of the £45m redevelopment is now being unveiled, the centrepiece being a new central staircase.
Project Manager Sarah Younger, gave the BBC a glimpse of the new look Tate Britain just days before its official unveiling.