Open House London, the capital's largest architectural festival, will take place on 18 & 19 September 2010. The initiative is a simple but powerful concept: hundreds of great buildings of all types and periods open up their doors to all, completely for free.

This unique opportunity to access and understand architecture is a challenge to look at everyday buildings anew, and communicates the value of a well-designed city to everybody who uses it. It is London's biggest architectural event and Freemasons' Hall has taken part very successfully for the last few years.

The Grand Temple and vestibules are opened to the public and a self-guided tour route is set up to pass through the Library and Museum, Robing Room, processional corridor and exhibition area on the Ground floor with visitors exiting past the Shop. Last year there were more than 2,000 visitors on the day.

For more information about the event generally see http://open-city.org.uk/activities/london/index.html