How can we manage, improve and develop resilient, sustainable communities, without a solid scientific knowledge of our built environment? Our everyday life is framed by a cohort of buildings about which we know very little, or nothing: they are outside of our cultural concerns, even though we reside, work, learn or convalesce in them. Understanding the architecture that shapes our everyday empowers our communities – it enables them to take informed decisions about what to preserve, reuse and replace; how to update and improve their buildings. At a time when resources are dwindling and must be used rationally, repurposing and retrofitting existing buildings is a priority over new construction, everywhere. European societies have a vast building stock at their disposal, erected in the second half of the past century, to be used and transformed: sturdy, pragmatic objects whose features are seldom discussed. ReARQ.IB bridges the gap between local communities in Spain and Portugal and their ‘architecture of proximity’: structures, ensembles and neighbourhoods generally left out of canonical historiography, close to our lives but far from our minds. Making the genetic fabric of this built environment clear, intelligible and operative is an essential first step for responsible management and decision-making by stakeholders. Contemporary architecture in both countries may be celebrated in professional circles, and even enjoy public visibility – but communities across the Iberian Peninsula, including many designers, know precious little about their modern built environment, which grew exponentially in the 20th century. Focusing on public-use and residential buildings – prevalent generic typologies that concern most communities – ReARQ.IB will integrate information and critical enquiry to support management and action while advancing architectural and urban history. This is applied science for community participation enabling a more sustainable and resilient built environment