The paper deals about significant projects of large scale mapping at the beginning of 19th century in the Habsburg Empire. They have been already based on uniform geodetic horizontal control. Basic parameters and features of Second Military Survey in the territory of the Czech Lands as well as links with project of Stable cadastre are delineated. Technology of establishing the horizontal control (1st order trigonometric networks) is described in detail. Qualitative parameters of geodetically measured data and the survey documentation are analysed. Accuracy analysis of angular measurements and methodology of co-ordinate computations in the Gusterberg coordinate system are also discussed.By means of identical points the horizontal control enables unambiguous transformation from the Gusterberg and St. Stephen co-ordinate systems into the national co-ordinate system (JTSK) or WGS 84 with the accuracy higher than graphical accuracy of original maps. This transformation, published here as the global transformation key (GTK), is of great importance. The results of tests of GTKs compiled separately for Bohemia and Moravia+Silesia together with the analysis of contact zone of both above mentioned historical co-ordinate systems are introduced.As an example of GTK application georeferenced map sheets from Second Military Survey are presented. GTKs are of fundamental importance in unification of heterogeneous geodetic information files of cadastre of real estates in the Czech Republic.