This book presents the proceedings of the 4th International Symposium on large Spatial Databases, SSD '95, held in Portland, Maine, USA in August 1995.The 23 refereed full papers presented were selected from more than 60 submissions and describe the state-of-the-art in the expanding field of large spatial databases, with a certain emphasis on an upcoming new generation of spatial database management systems. The volume is organized in sections on spatial data models, spatial data mining, spatial query processing, multiple representations, open GIS, geo-algorithms, reasoning about spatial relations, spatial joins, and benchmarks.