This paper presents work that creates a Geographical Information Systems (GIS) database of European census data from 1870 to 2000. The database is integrated over space and time. Spatially it consists of regional-level data for most of Europe, temporally it covers every decade from 1870 to 2000. Crucially the data have been interpolated onto the administrative units available in 2000 thus allowing contemporary population patterns to be understood in the light of the changes that have occurred since the late-nineteenth century. The impact of interpolation error on the resulting estimates is explored. This database will provide a framework for much future analysis on long-term Europe-wide demographic processes over space and time.