Instead of hiding the structure behind a skin, Shanghai-based studio Xiang Architects turned the staircase itself into the load-bearing frame of the Chenhu Migratory Bird Observation Tower. Rising 19.8 metres (65 feet) above the wetlands of Wuhan’s Chenhu area in Hubei Province, the tower replaces the conventional central core with a staircase that carries both circulation and structural load. The design removes the one element most observation towers rely on — a closed shaft at the centre — and puts the walking path in its place.
A structural double helix organizes the entire tower. Two independent, counter-rotating flights create separate paths for ascending and descending, interlocked with continuous steel braces that resist the torsion the twisting geometry would otherwise generate. Stair treads, platforms, and diagonal supports form repeating triangular units along the height of the tower, so the counter-rotating stair engineering does the job usually assigned to a hidden core — visibly, in the same plane the visitor occupies. For Xiang Architects, the approach tests how far a staircase can double as a primary structural element rather than a secondary means of vertical access.
Twenty-four staggered platforms break the ascent into a measured rhythm, arranged along a spiral path in the spirit of other towers built around switchback movement, like the ascent up Rare Studio’s La Vuelta al Monte tower in Argentina. Each flight is organized into 9-step units with 1.5-metre (5-foot) elevation intervals, alternating steady climbing with brief pauses at each platform. As the double-helix path rotates, orientation shifts by roughly 30 degrees at every level, so the migratory bird observation tower never offers the same vantage point twice on the way up.
A shifting sightline replaces the usual climb-straight-to-the-top logic of viewing towers. Near the base, the view is close and textured — tree canopy, riverbank, the grain of the ground — while higher up it opens toward the wetland’s water system and the horizon. Each turn in the stair introduces a new direction rather than a wider version of the last one, breaking what would otherwise be a single 360-degree wetland view into a sequence that only resolves into a full panorama at the summit.
A 3-metre void (9.8 feet) runs through the centre of the tower, in the space a structural core would normally occupy. With the counter-rotating stairs and braces carrying the loads instead, this open-core tower architecture leaves the shaft empty and the structure exposed rather than hidden behind finishes — its geometry changing as the body moves through it.
Twenty-four prefabricated modules made the geometry buildable. To manage the continuously varying curvature of the double helix, the design was broken down through parametric modelling into 24 standardized units, each combining stair treads, platform plates, and their structural connections. This parametric steel fabrication approach let a non-repeating form be produced with a single, unified logic rather than site-by-site improvisation.
Off-site fabrication and bolted assembly kept the geometry precise. Each module was cut, welded, tested, and corrosion-treated in a factory before being shipped to the site for layered installation, connected primarily through bolted joints to minimize on-site processing. The tower’s outer skin — curved steel plates finished in a matte silver coating — forms a continuous, monolithic surface over this prefabricated steel tower construction, reading the light differently depending on the weather: catching direct sky on clear days, softening at the edges in mist, and picking up warm tones at dusk.
A wintering ground for wetland birds shaped the site itself before the tower did. The structure sits atop Xianglushan, a natural high point roughly 22 metres (72 feet) above sea level overlooking Tonghu Town and the Tongshun River. Between October and March each year, the surrounding marshland becomes a stopover for more than 100,000 migratory birds, and the brief for the tower — how to build vertically on an otherwise flat, horizontal site — followed directly from that seasonal presence. Rather than imitate the wetland’s forms, the tower asserts a clear geometric presence within it, an approach shared with other wetland tower architecture in China, like the SCUT Lunar Tower rising from mangrove wetlands, rather than a camouflaged lookout.
The last platform doesn’t just end the ascent; it restores, all at once, the 360-degree view that the climb spent 24 platforms breaking apart. What stays with the visitor afterward isn’t that summit view alone, but the 3-metre gap at the centre of the tower — empty for its entire height, and doing the structural work a solid core never had to.
Chenhu Migratory Bird Observation Tower by Xiang Architects | Location: Tonghu Town, Caidian District, Wuhan, Hubei Province, China — Year: 2026 — Key materials: steel structure, matte silver-coated steel cladding