Nowadays the suburbs built after the World War II is now considered as heritage. Tapiola garden city is a one of the pioneer of city suburbs in Finland. It is situated in Espoo, next to Helsinki. The garden city's construction was started from 1950s, and still it is growing. The whole area is regarded as National Built Environment and also National Landscape. Although the project of stretching metro from the centre of Helsinki is now ongoing. This paper concerns how Tapiola garden city manages between conservation and development, and also the system of inventory, evaluation and city plan.