Below is a list of internet links that allow you to download free GIS data.
We appreciate your input and should you know of any other sources, we would be happy to add them to our list.
Tip: ArcGIS provides numerous data like road maps, topogr. Maps, satellite photos, etc. as basemaps directly in the program. To add a basemap to your project, go to "File -> Add Data .. -> Add Basemap .." and select the desired basemap.
Tools for Setting Geological Maps
ESRI mapping center
Color Ramps, Symbols and more
Satellite and Areal Photos
LandSAT, Corona, etc.
Global Land Cover Facility
Digital Terrain Model
SRTM, Aster GDEM, GTOPO30
European Environment Agency
Various environment data
Statistical geobasis data of the EU