Nowadays, location-based services based on GPS and map data are commonly available. Since GPS does not work in buildings and map data provide geographic information only, such services are limited to outdoor scenarios. Large research effort has been carried out to explore indoor positioning and navigation systems but up to now mostly proprietary and isolated solutions have been proposed. In the project MapBiquitous an integrated system for indoor and outdoor location-based services is developed. It is based on a decentralized infrastructure of building servers providing information about the building geometry, positioning infrastructure and navigation. Building servers are dynamically discovered and provided information is seamlessly integrated into outdoor systems by the MapBiqutious client which runs on a mobile device.