In Japan, buildings that are more than 30 years old have been deemed worthless because of the uniform real estate evaluation system.It is a fact that old buildings get difficult to comply with earthquake, floor plan adapted to the demand, universal design, updated building law, etc. However, in most of the case, the skeleton (the building itself) is still useful. All of these building has the potential to be reborn by conversion and transformation with a value that cannot be created by new construction.Saiseikenchiku-Laboratory(再生建築研究所) is a multi-boundary practice to create new architecture with tons of the abandoned but hidden resources of buildings.