When Buildings Rise, What Does the Ground Become?

Beneath elevated structures across cities worldwide—under pilotis, highways, and rail viaducts—lie spaces that exist in a state of ambiguity. Neither fully public nor private, they are colonised informally by vendors, shelters, and spontaneous gathering points. Architectural media outlet ArchDaily recently spotlighted this phenomenon, presenting ten global projects that are actively reshaping what happens at ground level beneath elevated architecture.

Why the Space Below Matters Now

Le Corbusier's concept of the pilotis, formalised in the early twentieth century, was visionary in intent: lift buildings on columns, liberate the ground, and return it to the public. A century later, that promise has largely gone unfulfilled. The spaces beneath elevated structures are often dark, unclaimed, and disconnected from the surrounding urban fabric.

According to industry reports, these in-between zones resist easy categorisation. Exposed to weather, subject to noise and pollution, and frequently severed from adjacent neighbourhoods, they become spatial residue. When infrastructure—highways, railways, transit systems—scales this condition up, entire urban territories are fractured.

Yet these spaces are never truly empty. Informal markets, temporary shelters, and impromptu community spaces emerge where planners left nothing. The underside of infrastructure becomes a stage for unplanned urban life, demanding that architects and planners take responsibility for what they leave behind.

From High Line to Under-Space: A History of Looking Down

The conversation is not new. New York's High Line, which opened in 2009, demonstrated the transformative potential of elevated rail infrastructure—though its focus was the top, not the bottom. Since then, global attention has shifted downward.

In Europe, EM2N in Zurich refurbished railway viaduct arches into active urban space, while José Adrião Arquitetos recast Lisbon's Fonte Nova Square beneath a highway overpass into a civic plaza. MVRDV's One Green Mile integrated greenery and pedestrian axes into an infrastructure underpass.

Across Asia, similar moves are underway. China's Wuxiang 987 High Line Park and Taiwan's Taichung Green Corridor by Mecanoo have transformed rail underbellies into linear parks and ecological corridors. Seoul's Eungbong Terrace by YZA signals that South Korea is joining this shift. In Istanbul, KAAT Architecture converted infrastructure underbelly into a cultural venue; in India, Aangan Collaborative LLP reclaimed informally occupied under-structures as community space.

Outlook [AI Analysis]

As cities densify and infrastructure expands, under-structure space is likely to gain strategic importance. In land-scarce urban cores, activating existing residual space offers cost and regeneration advantages. Integrated design approaches—planning ground-level programming from the outset—are likely to spread across the architecture and urban planning industries.

Governance challenges are also likely to surface: the ambiguous ownership of these spaces will require clearer legal and administrative frameworks if isolated projects are to scale into systemic change. Architecture's aspiration to lightness is only complete when it takes full responsibility for the ground it leaves behind.