Over 20 years ago, Stuart Hall posed the question, 'Whose heritage?' (Hall, 1999). Hall's call for the critical transformation and reimagining of heritage and nation, for 'un-settling "The Heritage" and re-imagining the post-nation', remains as urgent as ever. In the context of the ongoing disparate impacts of the Covid-19 pandemic and the global re-ignition of the Black Lives Matter movement, 'a national collection' cannot be imagined without addressing the structural inequalities in the arts, debates around 'contested heritage', and the difficult and contentious histories imbued in objects. Transforming Collections: Reimagining Art, Nation and Heritage aims to build on decolonial feminist approaches and creative machine learning (ML) development: to enable digital cross-search of collections, to surface patterns of bias, to uncover hidden and unexpected connections, and to thus open up new interpretative frames and potential narratives of art, nation and heritage. Transforming Collections seeks to address the following questions: - How can we counter structural biases and decentre white Western narratives in our cultural collections? (Wekker, 2016; Olusoga, 2016) - How can we surface suppressed histories, amplify marginalized voices, and reevaluate artists and artworks ignored or sidelined by dominant narratives? - How can we transform the architectures and 'algorithms of oppression' (Noble, 2018) that underpin collections and reproduce inequalities and erasures? - How can we imagine a distributed yet connected 'national collection' that builds on and enriches existing knowledge, with multiple and multivocal new narratives? - How can we reimagine art, nation and heritage through collections as part of the wider 'digital cultural record' (Risam, 2019)? Transforming Collections is an interdisciplinary collaborative project led by University of the Arts London (UAL) with Tate, home to the national collection of British art from the 16th century and an international modern and contemporary art collection. The project will be led by a core team from UAL's Decolonising Arts Institute and Creative Computing Institute, working closely with Tate as an Independent Research Organisation (IRO). In addition to Tate, Transforming Collections has nine project partners and four collaborating organisations across the UK, representing significant public collections as well as major arts charities and key archives of different scales. These are: Arts Council Collection, British Council Collection, Birmingham Museums Trust, Glasgow Museums, Liverpool Museums Trust, Middlesbrough Institute of Modern Art, Wellcome Collection, Art Fund, Contemporary Art Society, Art UK, the JISC Archives Hub and Iniva (Institute of International Visual Art). We also have an international project partner in the Van Abbemuseum, Eindhoven, who will host a major project conference in year one. The project adopts a braided approach enfolding 1) Critical art historical and museological research with 2) Creative machine learning development and participatory design and 3) Artists digital commissions as interventions into collections. Building on the insights and emerging findings of the Tate-led TANC Foundation project, Provisional Semantics (2020-22), and the UAL-led projects, AHRC Black Artists and Modernism (2015-18) and UKRI MIMIC project (Musically Intelligent Machines Interacting Creatively, 2018-21), Transforming Collections approaches the challenge of 'dissolving barriers' as a problem of knowledge and power - not only a question of what becomes visible, legible, accessible, but also how, and for whom. As such, Transforming Collections aims to model and test new and sustainable ways of searching across collections; to expose in-built inequities in collections data; to reconnect, recontextualise and reinterpret the work of 'artists of colour'; and empower diverse stakeholders in discovering the sometimes uncomfortable stories that collections.