Suomi.fi-maps offers to the public administration and government agencies a centralized service for utilizing maps and location data. In the Suomi.fi-maps service, a user may compile their own map views from the map layers available in the service, as well as from their own objects and materials provided by service interfaces of their own organization. Oskari platform is used to implement the Suomi.fi-maps system. Suomi.fi-maps is used to enable all the Finnish residents to use maps and the location data to find about the services they are interested in. In addition to other open data the open materials of the National Land Survey may also be used: various terrain and background maps, property boundaries and aerial photographs. User may connect their own interfaces to the Suomi.fi-maps service or add their own objects to the map to be published. This presentation describes with examples, how the Oskari platform and its features are used used to implement the Suomi.fi-maps service and lessons learned.