GREENGAGE’s vision isto promote innovative governance and help public authoritiesin shaping their climate mitigation and adaptation policies by engaging with citizens to co-create green initiatives and to develop Citizen Observatories (CO), focusing on mobility, air quality and healthy living supporting the delivery of carbon neutral neighbourhoods. The pan-European research innovation action will develop innovative governance process deploying digital solutions to transform citizen’s engagement and cities’ effectiveness in delivering European Green Deal objectives for carbon neutral cities. Green and digital transformation to carbon neutral cities will be promoted via two interrelated project dimensions. First the enhancement of intelligence applied to city decision making process and governance by engaging with citizen observations integrated with Copernicus, GEOSS, in-situ and socio-economic intelligence, and delivered by innovative governance models based on novel toolboxes of decision-making methodologies and technologies. Second by harnessing the social and cultural opportunities to promote the active engagement of citizens via COs in the collection and use of urban decision-making intelligence supportThe project will achieve the above vision by facilitating citizens to observe and co-create their cities by sensing their urban environments that will complement, validate and enrich information held by the public administrations and/or environment agencies derived from remote sensing data and obtained via other authoritative observations. This enhanced and evidence-based information will be used for smart urban governance including policy evaluation, policy making and decision making. GREENGAGE increases societal awareness by showcasing the environmental challenges (climate change, poor air quality, healthy living) through ‘as-is’ state of the urban environment, highlighting the information and other gaps in the authoritative data held by the public administ