Mulegns, Julier Pass, Swiss Alps, August 13, 2025
News Summary
Tor Alva, also called the White Tower, is a 30‑metre, four‑storey modular tower built with robotic 3D printing of hollow concrete columns. Designed and fabricated using coordinated robot arms, a fast‑hardening soft concrete mix and embedded reinforcement, the structure uses dry connections and removable fastenings so it can be disassembled and re‑erected elsewhere. The tower houses a vaulted top‑floor concert space and twisting interior rooms, and was developed with industry partners to explore circular construction, lower lifetime waste and strategies to extend service life despite material trade‑offs in embodied carbon.
ETH Zurich unveils Tor Alva: a 30 m, four‑storey modular 3D‑printed concrete tower on the Julier Pass
A new concrete tower called Tor Alva has been unveiled in Mulegns on the Julier Pass in the Swiss Alps. The structure reaches 30 metres tall including its base and is a four‑storey, modular building designed for cultural events and reuse. The project was completed in May 2025 and opened to the public for guided tours from 23 May 2025. Staged performances are set to begin in July 2025.
What makes the tower notable
Tor Alva is described as the world’s tallest 3D‑printed concrete tower. Its load‑bearing columns were fully produced by robotic 3D printing and include built‑in reinforcement, a first for a multi‑storey structure of this kind. The design is modular so the tower can be dismantled after its planned five‑year stay in Mulegns and re‑erected elsewhere using removable screws and dry, prestressed joints rather than glued or permanent connections.
Design, use and interior
The tower was commissioned by a local cultural foundation and designed by architects working with ETH Zurich research teams. The structure contains branching, twisting hollow columns — described as some 32 branches that wrap around a series of interior rooms — and includes vertical stairs and a vaulted top‑floor concert space with views over the Julier valley. The outer face is windowless and shows a criss‑cross texture typical of layered extrusion printing. At night the tower is illuminated and can change lighting color for performances and events.
How it was built: robots, material and joints
Construction began with printing of the columns. On 1 February 2024 a robot at ETH Zurich began printing the first columns; eight lower‑floor columns were printed in Zurich and later assembled on site in May 2024. The technique used a soft concrete mix extruded in thin layers to form hollow, joint‑based columns without conventional formwork. The concrete was developed as a fine‑grain mix with a custom additive so each layer hardened quickly enough to support the next.
The printing workflow used coordinated robotic fabrication with two robots: one extruded layered concrete into freeform shapes while a second robot placed reinforcement between layers. The reinforcement strategy combined embedded horizontal stainless steel rings during printing with vertical rods placed after printing; vertical cavities were then filled with self‑compacting mortar. Upper sections include prestressed rods to improve crack resistance. Stainless steel was chosen to reduce corrosion risk and extend component life.
Environment and reuse
The project was developed with circularity in mind. Components are modular and connected with removable screws and prestressed joints so they can be taken apart and reused. Designers also included measures intended to accelerate concrete carbonation so the material can reabsorb some atmospheric CO₂ over time. The team acknowledges the specialized printing mix has a higher carbon footprint than some conventional mixes, and they combined material choices, reuse planning, and printing geometry that saves mass to reduce overall environmental impact.
Collaboration and context
ETH Zurich led the research and development effort through several groups including the Digital Building Technologies group, the Institute of Structural Analysis and Design (CSBD), and the Institute of Building Materials (PCBM). The work was carried out within the framework of the National Competence Center Digital Fabrication and with support from an academic foundation, local community groups, private donors, industry partners, and two ETH spin‑offs. Industry partners included major materials and chemicals firms, while the robotic and software tools came from university labs and spin‑off companies.
Where Tor Alva fits in a wider research push
The tower is one among several recent experiments in robotic and low‑carbon construction at ETH. Other projects from the same research ecosystem include a reusable vaulted formwork system that cuts concrete and steel use, and an impact‑printing process aimed at low‑carbon, cement‑free building materials. The combined work brings together computational design, automated fabrication, structural engineering and materials science to test new ways to make and remake buildings.
Timeline and visitor information
Printing of columns started 1 February 2024, on‑site assembly of printed columns took place in May 2024, and the project was completed in May 2025. The tower was unveiled on 20 May 2025, opened for guided tours on 23 May 2025, and will host performances beginning in July 2025. The plan is for Tor Alva to remain in Mulegns for around five years before being taken apart for reuse elsewhere.
Credits and documentation
The project was documented by several photographers and covered in technical writeups that detailed the design, fabrication and materials strategies. The work drew on robotic fabrication facilities and computational design tools developed at the university and with industry collaborators.
FAQ
Is Tor Alva open to the public?
Yes. Guided tours began on 23 May 2025 and the tower will host public performances from July 2025.
How tall is the tower?
The tower measures 30 metres in height including its base and has four storeys.
How was the structure made?
The load‑bearing columns were 3D printed with a soft concrete mix in thin layers. Two robots worked together: one extruded the concrete, the other placed reinforcement during printing. Vertical rods were added after printing and rods were tensioned or prestressed in some upper sections.
Can the tower be reused?
Yes. The tower is modular and designed to be taken apart and rebuilt. Components use removable screws, dry connections and prestressed joints to make disassembly and re‑erection possible.
Is the tower environmentally friendly?
The team used measures to reduce impact, such as stainless steel for durability, geometry that saves material, a carbonation strategy, and a reuse plan. The specialized printing mix does have a higher embodied carbon than some alternatives, which the team sought to offset through these measures.
Who led the project?
The project was led by research groups at a Swiss technical university, in partnership with local cultural commissioners, industry partners, spin‑offs and community supporters.
Key features at a glance
| Feature | Detail |
|---|---|
| Project name | Tor Alva (the White Tower) |
| Location | Mulegns, Julier Pass, Swiss Alps |
| Height / Storeys | 30 m including base / 4 storeys |
| Construction method | Robotic 3D printing of hollow columns with coordinated reinforcement |
| Materials | Fine‑grain soft concrete with custom additive; stainless steel reinforcement; self‑compacting mortar for cavities |
| Modularity | Designed for disassembly with removable screws, dry connections, and prestressed joints |
| Use | Cultural venue for tours, art, music and staged performances |
| Key timeline | Columns printed from Feb 2024; on‑site assembly May 2024; unveiled 20 May 2025; tours from 23 May 2025 |
| Planned duration on site | About five years, with option to relocate |
| Research leads | University digital fabrication, structural design and materials groups in partnership with industry and spin‑offs |
Deeper Dive: News & Info About This Topic
Additional Resources
- 3D Printing Industry: ETH Zurich unveils Tor Alva — world’s tallest 3D‑printed concrete tower
- Wikipedia: Tor Alva
- designboom: ETH Zurich lightweight reusable formwork system (19 Feb 2025)
- Google Search: ETH Zurich reusable formwork
- designboom: 3D‑printed White Tower — Tor Alva (7 Feb 2024)
- Google Scholar: Tor Alva ETH Zurich
- Archinect: ETH Zurich develops robotic process for impact printing earth materials
- Encyclopedia Britannica: impact printing earth materials
- VoxelMatters: ETH shows robotic AM method for sustainable construction
- Google News: ETH robotic additive manufacturing sustainable construction
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