“A New Model of Urban Public Architecture: a ‘Living Room’ for the Community”

Bridging Kanda and Akihabara Through Integrated Urban Development Across Both Riverbanks

The site is located on the border between Kanda, an area that has retained the charm and human warmth of Tokyo’s traditional downtown since the Edo period, and Akihabara, which has evolved from a market district into a world-renowned hub for electronics, anime culture, and inbound tourism. On the opposite bank of the Kanda River, the red-brick remains of the Old Mansei-bashi Station (1912 - 1943) have recently been repurposed into a revitalized commercial facility. This project is more than a simple reconstruction of the Mansei-bashi branch of the Chiyoda City Office. It has been conceived as a critical element in a broader urban development vision, aiming to bridge the Kanda and Akihabara districts and foster cohesion on both sides of the river. Kanda and Akihabara are fundamentally different in both functions and appearances. Within this unique context, the envisioned architecture does not favor one side over the other. Instead, it seeks to open simultaneously inward and outward, establishing connections with the natural environment while resonating with the urban fabric. By emphasizing the Kanda River as a central axis and using bricks that carry the memory and historical legacy of the area as a shared heritage, the project aims to create a facility that enriches and supports the lives of local residents.

A Flexible Interface Resonating with City and Environment

The exterior design was conceived as a new landmark for Mansei-bashi, harmonizing with the contrasting urban landscapes of Akihabara and the Kanda River. Known as a global hub of digital culture and cutting-edge trends, Akihabara is defined by its dynamic, diverse energy, often characterized by an uncontrollable vibrancy. In contrast, the banks of the Kanda River, characterized by the calm and stately heritage of the Old Manseibashi Station, present a more subdued and static atmosphere. The design seeks to merge these two disparate identities through its architectural expression. Brick, as a material, carries a unique tactile authenticity, with each piece individually crafted and laid by hand. By layering these bricks into dynamic, three-dimensional forms, the façade responds to the duality of its urban context, capturing the vibrancy of Akihabara while respecting the historical gravitas of Kanda.

The “Brick Shade,” a structure formed by layering bricks in three dimensions, is intended to serve as a landmark that harmonizes with the surrounding environment, the urban fabric, and the passage of time. As the redevelopment along the Kanda River begins with this project, its approach—integrating the river, embracing the historical heritage, and bridging both riverbanks - positions it as a flagship initiative for cohesive urban development and landscape design.

The “Brick Shade”: An Environmental Device Promoting Water Circulation and Green Growth

The "Brick Shade" employs 100mm square bricks as its fundamental unit, layered into three-dimensional structures that serves as an environmental system that circulates water and fosters greenery. This passive ecological mechanism provides shading, controls sightlines, facilitates airflow and water drainage, and incorporates a water-retention system. It serves as a symbol for environmentally friendly equipment in public facilities and is intended to promote green growth. The retention system channels rainwater collected on the rooftop through structural columns, that function as water pipes, enabling a gravity-fed irrigation process. This passive system underscores the building’s commitment to environmental sustainability while serving as a visual educational tool for visitors. Exposed rain barrels and drainage systems on the rooftop invite residents and children to engage with the building’s environmental functions, encouraging learning and awareness. The adoption of passive environmental strategies, including the Brick Shade, has enabled the building to achieve a planned CO2 reduction rate in excess of 40%.

A Community Hub for Connection and Growth

Despite its compact scale, the building accommodates eight distinct functions: a branch office, multi-purpose spaces, a kitchen studio, a child welfare facility, a tourism office, a social welfare council, community center rooms, and a civic hall. Embracing the diversity of its users and purposes, the design celebrates its multi-functional nature, transforming a typical mixed-use building into an intentional and cohesive structure. The design of each floor was informed as a result of grassroots hearings and community research, ensuring that spaces respond to their specific uses while being unified through verandas clad in the Brick Shade. A "living room" concept for the community is central to the design, serving as inviting space where residents, seniors, children, professionals, and families can gather, fostering intergenerational connections. Balconies, envisioned as semi-outdoor engawa spaces, are key to this open and inclusive design.

Semi-Outdoor Third Spaces as Engawa

The floor plan is elegantly simple, comprising essential office spaces, a minimal core housing staircases, restrooms, and elevators, and connecting corridors. At the intersection-facing corner, a deep balcony offers a multi-functional engawa space, providing shading, a safe evacuation route, and a welcoming semi-public third space. This balcony, capable of being subtly enclosed, exemplifies an open yet adaptable public space. During the period of COVID-19 pandemic, its unique semi-outdoor design—being both ventilated and sheltered—proved invaluable, offering a rare combination of safety and versatility. This feature underscores the building’s role as a resilient and multi-purpose public facility in times of both normalcy and crisis.

Project Overview

Project Name: Mansei-bashi Branch Office/Citizen Hall
Usage: Municipal Office, Administrative Office, Child Welfare Facility
Location (Prefecture, City): Sotokanda, Chiyoda City, Tokyo
Site Area: 551.15 ㎡
Total Floor Area: 3653.68 ㎡
Number of Floors: 9 above ground, 1 below ground
Height to Eaves / Maximum Height: 37.885/39.35 m
Primary Structure: Steel (S) with partial Steel Reinforced Concrete (SRC)
Completion Date: 2020/12/1

Credits

Client: Chiyoda City
Scope: Basic Design, Detailed Design, Construction Supervision
Construction Companies: Building: Taisei Corporation and Honma Construction JV
Electrical: Daito Corporation and Marumo Construction JV: Shiroguchi Kenkyujo (HVAC & Plumbing) and Toyo Construction (JV)
Elevator: Hitachi Building Systems Co., Ltd.
Photo Credit: SS Co., Ltd.