This article reconceptualises public art exhibitions in the UK as spatial-aesthetic and institutional devices that organise urban relations. By developing a unified Lefebvrian spatial grammar, it reads cases at two scales: a micro triad (representations of space, spatial practices, and spaces of representation) and a macro diagnosis (abstract, contradictory, and differential space). Archival, curatorial, and media sources — newsreels, press, letters pages, and institutional records — ground analyses across: the Festival of Britain and the exhibition, ‘This Is Tomorrow’; Rachel Whiteread's House and Antony Gormley's Sculpture for Derry Walls; Black Arts Movement-aligned murals in Brixton and the Bogside; the ‘Fourth Plinth’; Assemble's Granby Four Streets; and the festival ‘Lumiere Derry∼Londonderry’. The study specifies four tests for assessing when exhibitionary projects tend towards spatial justice from redistributed authorship/decision rights, changes in ownership/tenure, recognised and resourced care, to persistence of public voice. Findings challenge linear narratives from spectacle to participation, showing instead patterned continuities, frictions, and conditions under which differential practices can be made durable.