GreenKeys is part-financed by the European Union Community Initiative INTERREG III B CADSES and the German Federal Ministry of Transport, Building and Urban Affairs UNLOCKING GREEN SPACE: PERCEPTIONS AND ATTITUDES ON VARIOUS ASPECTS OF URBAN GREEN SPACE Dr. Paschalis ARVANITIDIS Department of Economics Department of Planning and Regional Development, University of Thessaly, Greece September 2007 URBAN GREEN AS A KEY FOR SUSTAINABLE CITIES