Heritage Open Days 2009, an initiative that aims to provide members of the public with the chance to visit more than 4,000 historic sites between 10-13 September, has been launched in Brighton, East Sussex.

This year's scheme, which aims to attract more than one million people to a range of properties across the country, is being administered by English Heritage after the previous organisers, the Civic Trust, entered administration earlier this year. Among the sites set to open to the public is a labyrinth of tunnels built as air-raid shelters during the Second World War in Stockport, Greater Manchester, and Morecambe Winter Gardens in Lancashire, which have been closed since 1977.

Baroness Andrews, English Heritage chair, said: "Heritage Open Days are an opportunity to explore places which, however familiar, are normally closed and therefore mysterious. They provide a chance not only to discover secret history, but to meet the people who live or work there, and are passionate about their subject."