This volume collects 22 papers presented at the 4th International Symposium of the ICA Commission on the History of Cartography, held at Eotvos Lorand University, Budapest, Hungary, on 28-29 June 2012. The overall conference theme is 'Exploration - Discovery - Cartography', but preference has been given to papers dealing with cartography in the 19th and 20th centuries.  The papers are classified according to regional sub-themes, i.e. papers on the Americas, papers on Africa, etc.