The full title of this project with acronym GENCENG is "Development of a Geo-ENvironmental information system for the region of CENtral Greece". A GIS is based on a spatial database system (SDBS). In order to support spatial objects in a database system several important issues must be taken into account such as: spatial data models, indexing mechanisms and efficient query processing. An SDBS is a database system that offers spatial data types in its data model and query language and supports spatial data types in its implementation, providing at least spatial indexing and efficient spatial query processing. Spatial database systems has been an active area of research over the past twenty years.