High above the Aare river

Just a few kilometers outside the city of Solothurn lies the former Attisholz cellulose factory, now one of the largest development sites in Switzerland. Over the past few years, a wide variety of uses have emerged on the former industrial site, transforming it into a vibrant meeting place. Live concerts, gastronomy, street art, and generous open spaces draw a diverse audience to this unique riverside location along the Aare.

Currently, new spaces for living and working are being created on the Attisholz site. A striking centerpiece is the former warehouse located directly on the riverbank, now undergoing expansion and serving as the base for a vertical addition. Rising above the existing structure will be three new volumes: two four-story buildings and an eleven-story high-rise. In total, the project will deliver over one hundred privately owned apartments ranging from 2.5 to 5.5 rooms.

The new residential buildings continue the industrial character of the original structure. Their deep burgundy color references the surrounding context, while the wave-shaped aluminum cladding echoes the nearby river landscape. Floor-to-ceiling windows offer sweeping views over the Aare toward the Bernese Oberland and the Jura mountains. At the corners of the buildings, transparent balconies project outward, articulating the three-part ensemble and lending a sense of lightness to the vertical extension.

The base level—formed by the existing structure and a new replacement building—will house a theater, workshops, gastronomy, commercial, and service spaces. Above the four- to five-story base sits a new intermediate floor, designed to distribute the structural loads of the residential units above. Along the south façade, it includes a mix of small and large apartments, while the north side features shared spaces such as a community room.

A particular highlight is the rooftop garden that crowns the building: this green oasis sits high above the Aare and offers residents a place for connection, relaxation, and shared urban gardening.

Type of Commission: Work Group Competition, 1st Prize
Client: Halter AG, Schlieren
Location: Attisholz Site, Riedholz, SO
Program: Residential and commercial spaces, gastronomy, culture, and education
Planning Phase: August 2024 – December 2027
Construction Phase: Spring 2026 – Fall 2028
Sustainability: SNBS Site

Architecture: Stücheli Architekten, Zurich
General Contractor: Halter AG, Schlieren
Structural Engineering Work Group: Anliker, Emmenbrücke; Lüchinger Meyer Partner, Zurich
HVAC Engineering Work Group: Tschantré, Muttenz
Electrical Engineering Work Group: Jaisli Xamax, Dietikon; R+B Engineering, Brugg
Timber Construction: Blumer Lehmann, Gossau

Editorial: Stücheli Architekten, September 2025
Concept and Photography: Studio Willen
Text: Daniela Meyer
Visualizations: Indievisual
Design: Vieceli & Cremers

Stücheli Architekten AG
Binzstrasse 18, 8045 Zurich
www.stuecheli.ch

Temporary classroom building Campus Irchel, Zurich

A school,
that shows its colors

Over the next few years, several Zurich cantonal schools will have to be renovated. For reasons of sustainability, not every school will have its own temporary building. Instead, a temporary school facility for around 2,200 pupils and 300 employees has been built on the Irchel university campus. The facility is to serve as a changing area for eleven years. Two laboratory buildings and a courtyard building, which were built by Max Ziegler in 1978 and are now listed buildings, were converted for this purpose.

The change of use required extensive renovation measures to meet current standards. At the same time, the school had to be given its own face within the extensive university building. Color plays an important role in this: it gives the rooms a sense of authority and encourages the students to identify with their unusual high school.

Classrooms are now lined up in the former laboratory wings Y32 and Y34. The two classroom wings deliberately exude a provisional character after the conversion: the lightweight walls are clad with OSB panels and the pipes are visible beneath the ceilings. Coatings of paint distinguish the two wings from each other and divide the core-side wall surfaces of the sixty-meter-long corridors. The signage, which is characterized by an independent design language, also serves to provide simple orientation. In contrast to the interior spaces, the listed dark metal façade was left untouched. In the classrooms, it contrasts with the light-colored ceilings and wood-planked walls.

The courtyard building Y12, which has been converted into a cafeteria and media library, is particularly playful. Blue is reserved for the media library and is clearly visible through the glazed room endings. Two courtyards bring daylight into the canteen and are flanked by a red and a green bar, which form social meeting points. The traces of the old laboratory walls can be seen on the unfinished floor, while the canteen's toilet facilities look to the future: The pink and green WC is open to all genders and is a first for a Zurich school of this size.

Client: Hochbauamt Kanton Zurich
Location: University of Zurich Irchel
Construction sum: CHF 65 million
Floor area: 21,600 m2
Room program: Teaching and administration rooms, catering areas
Planning: July 2020 - December 2023
Realization: December 2021 - July 2024

Construction management: S+B Baumanagement, Winterthur
Civil engineer: Basler & Hofmann AG, Zurich
HLKKS: Polke Ziege von Moos AG, Zurich
Laboratory planning: Laboratory planner Tonelli AG, Gelterkinden
Signage: Zeichenfabrik, Zurich
Landscape: Schmid Landschaftsarchitekten GmbH, Zurich

Editorial: Stücheli Architects June 2025
Concept and photography: Studio Willen
Text: Daniela Meyer
Design: Vieceli & Cremers