Every city carries fractures within it — remnants, vacant lots, abandoned structures, and layers of surplus infrastructure that fall outside the spotlight of official planning. These are spaces out of sync with urban order, yet they unexpectedly form the city’s “underside,” where seemingly continuous structures begin to rupture.

In the drive to manage, forecast, and program everything, we rarely pause to observe what emerges from conditions that fall “outside the plan.” Yet it is precisely in such spaces that new urban forms of living begin to take root. Free from imposed rules or predetermined functions, they reveal another layer of the city — one that is always in a state of becoming, where new modes of occupation can surface.

Viewing the city through its voids rather than its solids shows that urban life exists not only in what has already taken shape, but also in what is still forming. In these unstable and unpredictable edges, the city reveals its capacity for self-renewal.

Terrain Vague: When Disorder Unlocks Potential

The concept of terrain vague, proposed by Spanish architect Ignasi de Solà-Morales in 1996, introduced a new way to interpret the “obsolete spaces” of contemporary cities. Drawing inspiration from photographers of the 1970s — who captured neglected areas in the post–World War II urban decline — he sketched an alternative map of the urban landscape.

In French, terrain and vague carry layered meanings: “empty,” “undefined,” but also “free” and “open-ended.” The term, therefore, captures the dual nature of these spaces — both estranged from familiar order and capable of evoking freedom, critique, and new identities.

For Solà-Morales, this ambiguity is precisely the strength of the void. Interspersed within the chaotic structure of contemporary cities, these spaces become fertile ground for difference — where the unexpected can be recorded, triggered, or amplified.

The Experimental City and the Invitation to Spontaneity

In an era when cities are increasingly shaped by markets, profit, and performance metrics, the leftover spaces between structures act as the system’s “fault points” — where practices outside standardized norms can unfold.

Unburdened by rigid planning, these voids function as urban laboratories: low-cost, yet high-impact. From informal markets, community gardens, and temporary installations to activities that challenge assumptions about security, justice, accessibility, or housing — such gaps allow diverse actors to operate quickly and flexibly.

Rather than pursuing large-scale reconstruction rooted in top-down logic, interventions in terrain vague are most effective when subtle: small, temporary actions shaped by the inherent qualities of the site. The goal is not to fill the void, but to listen — to let irregularity guide design.

Preserving spaces without predetermined programs can itself be an act of urban care. When each context is observed closely, we discover that voids create opportunities for unexpected forms of occupation — opening fissures through which the city can regenerate itself organically.

Practices of Activating the Void

Many global projects demonstrate that surplus spaces can be activated without erasing the ambiguity that makes them valuable. Rather than “domesticating” the void, these interventions highlight what is already present — the materials, the latent tension — through minimal gestures.

1. Pigalle Duperré Basketball Court (Paris) — Ill-Studio

A small parcel wedged between buildings transformed into a sports court through color, surface, and graphic composition — proving that impact comes not from scale but from precision in materiality and geometry.

2. Housing Prototype — SO-IL & MINI Living

A lightweight, almost invisible fabric structure that occupies the narrowest gaps between buildings to propose a vertical housing system — questioning traditional housing models and suggesting that solutions arise from reinterpreting voids.

3. Ashui Pavilion 2023 (Vietnam) — MIA Design Studio

On a neglected riverfront lot, a minimal structure of wood and fabric creates a community gathering space, drawing attention back to an area once dismissed as useless.

4. House 2 — Counter City (Switzerland) — Alice

Built underneath a bridge — an overlooked “infrastructural void” — the project transforms shadow and noise into spatial qualities for a temporary cultural program.

When “Not Building” Becomes a Design Strategy

These examples illustrate that activating a void does not require filling it. Instead, embracing its indeterminacy — and using minimal gestures to reveal its latent potential — allows the city to rediscover what planning has overlooked.

A void, therefore, is not an absence.
It is a resource — a vital pause that enables the city to imagine new ways of being.