The DVD-ROM has been produced within a project of the Czech Geological Survey “Geological maps of the territory of the Czech Republic and the Slovak Republic originating prior to the year 1918“. The major objective of the project was to provide, using interactive viewing, direct access to the collection of historical geological maps compiled before the year 1918. The collection contains 385 separate maps, 182 map supplements, 192 complementary texts, 50 explanatory notes, 85 graphical illustrations and 4 title pages. The maps depict in particular the territory of Bohemia, Moravia and Silesia (450 maps) and Slovakia (120 maps) and also adjacent central European regions (35 maps). An index of authors contains 107 biographical notes on distinguished authors including their contemporary portraits (only of half of the displayed authors). The material was chiefly assembled from the archive and library of the Czech Geological Survey. The maps which are not in possession of the Survey were borrowed from other 11 institutions: National Library of the Czech Republic, Prague, Library of the Academy of Sciences of the Czech Republic, Prague, National Museum, Prague, Faculty of Science, Charles University- basic library and map collection of the estate of Professor Kettner, Map collection of the Charles University, Prague , State Technical Museum, Prague, School of Mines – Technical University, Ostrava and the Czech Geological Survey – Geofond, Prague. The map set has also been supplemented by ten maps from the private collection of Dr. J. Kozák and maps from the State Central Mining Archive at Banská Štiavnica which provided material from archives and collections of Železorudné baně (Iron Mines) Spišská Nová Ves, the Main Bureau of Mines at Banská Štiavnica, Mining Captaincy in Spišká Nová Ves and State Directorate of Mines in Kremnica.