The Brighton Photo Biennial explores the theme Agents of Change: Photography and the Politics of Space. One theme of the Biennial is urban exploration: photographers picturing closed and hidden spaces of abandoned buildings, construction sites and underground tunnels.

In his Assaying history: creating temporal junctions through urban exploration paper Garrett says that the practice of urban exploration can be roughly defined as the discovery and exploration of unseen parts of the built environment, usually with a focus on derelict places. He adds:

Urban explorers are fascinated primarily in the flotsam of capital. They engage in a practice intensely interested in locating sites of haunted memory, seeking interaction with the ghosts of lives lived... These moments of encounter between the present and the past, experienced through physically exploring abandoned architecture, create flashes of confrontation with unexpected material traces that lead to emotionally charged discoveries through an embodied practice which mirrors the role of the archaeologist assaying surface material without deep excavation to analyse the character of places---a surface survey of affectation.

He argues that there is a place, a need, and a desire for embodied experiences of the past, dreams of alternative pasts, for localised historical interpretation and for unregulated decay because a ruin can point much more powerfully than a restored building to its historical and social genesis and because unregulated experiences in ruins tell us as much about ourselves as about the places we explore.

Ruins may be decaying, but they are not dead: they are places filled with possibilities for wondrous adventure, inspiring visions, quiet moments, peripatetic playfulness, and artistic potential.