Unveiled today (17 May) to coincide with the start of a major fundraising campaign, the proposals are part of a 10-year development project aimed at upgrading and expanding the existing Powell and Moya building.
The planned works are the largest since the museum - which claims to be the largest urban history museum in the world - was officially opened by the Queen in 1976.
The proposals will create 25 per cent more display space through 'reconfiguration', and make the museum more visible by building a new glass frontage along the 'forbidding' London Wall. There will also be a new cafe and an 'information zone'.
Jack Lohman, the director of the museum, admitted the time for a revamp was long overdue. He said: 'When the museum opened in 1976- [it] was a museum that breathed - architecturally, socially and intellectually. Nearly 30 years on, a reappraisal is called for.'
He added: 'As the fabric of London and visitors' expectations have evolved, the museum has tried to respond. But the effect over time has been one of patchwork. To renew [the building] needs visionary thinking.'