Map of Age of Central Helsinki Buildings By Jani Hannén link
Helsinki Region has a great open data website HRI where you can access various mapping data sets. It has a suitibly noble and practical philosophy that in the widespread use of this data can help everyone in Helsinki.
Open data increases citizens’ knowledge and understanding of their living area, its history and future development. This increases the overall activity, participation and interaction of citizens. Open data can be seen as a facilitator for creating new services and business opportunities, as well as supporting research and development. The value of public data increases the more it is used.
Buildings by age Greater Helsinki. By Topi Tjukanov. ref