The description and exchange of geospatial data using XML-based languages is currently a common practice. Two of the most widely adopted formats are the Geography Markup Language (GML) and Google’s Keyhole Markup Language (KML). Google Earth has very quickly become a popular Web based mapping software. In this chapter, we consider and elaborate a three step approach to visualize and publish geospatial data. Firstly, geospatial data are modeled in GML; secondly GML data are converted to KML; and thirdly KML data are published on the Web and visualized with Google Earth.