Open City is a London charity organization. Over the years they have organized the anual 'OpenHouseLondon' event, during which people can visit buildings that are normally closed to the public. The objective of the initiative is to pique the interest in architecture among the general public. The event organizes guided tours through buildings throughout the year, as well. Volunteers who wish to give tours or help with 'OpenHouseLondon' day can apply and are be registered via a 4D solution using their basic information, specific knowledge and which building and duties they would like to be in charge of. The entire organization of the event, the volunteers, and the buildings are managed by a 4D Server and a web interface, so that everybody who has access can organize and help. Any modifications can be entered quickly and safely.