Seamless civic canopy connecting city and nature

A free‑form roof that connects the city with nature

The facility brings together three programmes beneath a single sculptural roof: a semi-outdoor event plaza, an information centre and gallery, and a café. Each building sits independently beneath the flowing structure, allowing the architecture to follow the roof’s geometry while maintaining openness and flexibility.

Design details help dissolve the boundary between building and landscape. Sliding glass doors, perforated aluminium ceilings and durable concrete flooring allow spaces to transition seamlessly from interior rooms to sheltered eaves and into the park. The result is an accessible and welcoming environment that encourages people to move freely between city and nature.

To realise the roof’s complex form, we integrated structural engineering with advanced digital geometry. A triangular grid shell structure enables column-free spans of up to 46m, creating a generous covered plaza while preserving the roof’s light, organic character.

Coordinating architecture, landscape and infrastructure

A pedestrian deck known as the ‘The Path of Inspiration’ passes above the site, linking the north and south areas of the park. Its structural columns are positioned close to the new facility, requiring careful coordination with the roof structure.

Using digital modelling and collaborative design tools, we worked with the wider team to adjust the roof geometry in three dimensions, ensuring it avoided conflicts with the deck while preserving the architectural intent. The deck spans between the information and café buildings, visually linking the two structures while maintaining open views across the park.

This coordinated approach enabled architecture, infrastructure and landscape to work together as a continuous public environment.

Precision detailing for performance and durability

The roof arches span more than 46m and are formed from 270mm-wide steel plates cut from several-tens-millimetre-thick stock, connected by 250mm-deep built-T members. Connections were carefully detailed to align with the arch geometry, ensuring structural clarity and efficient on-site assembly.To resist the significant thrust forces generated by the arches, post-tensioned cables were embedded in the reinforced concrete foundations. This solution stabilises the structure while maintaining the roof’s slender appearance.

Detailing also considered the park’s natural setting and long-term maintenance. Structural members were designed without underside flanges to discourage birds from nesting, preserving the clean architectural expression. The information and café buildings align with the roof grid, while steel bracing ensures overall structural stability.

Through close collaboration between architects, engineers and contractors, the project transforms a complex structural challenge into a generous civic space. The lightweight roof, integrated with the surrounding landscape, creates a distinctive destination where people can gather and connect with nature. The project demonstrates how engineering can enable expressive architecture while enhancing urban life. In recognition of this achievement, our senior structural engineer, Kazuma Goto, received the 20th Japan Structural Design Award for his work on Rohto Heart Square Ume-kita.

_{Top image © SANAA}