White Tower (Tor Alva), Mulegns (Tower currently under construction)
Tor Alva (“White Tower”) is a 30-meter tall, 3D-printed building currently under construction in the alpine village of Mulegns, Switzerland. Upon completion in Spring 2025, it will stand as the world’s tallest 3D-printed structure. Designed for Fundaziun Origen, the tower functions as a beacon in the village and offers space for art installations and for music and theater performances. With its spectacular architecture and ground-breaking technology, the tower demonstrates the possibilities that computational design and digital fabrication offer the fields of architecture and construction. These include not only economic and ecological advantages, but they allow for an elaborate non-standard architecture with a bold wealth of shapes.
Architecture, Art and Culture
The white tower serves as a walk-in installation, an intimate concert venue, and as place of cultural mediation. The central design element of Tor Alva consists of 32 branching columns that enclose a sequence of abstract, atmospheric rooms. Visitors ascend through this vertical enfilade to reach the vaulted concert venue on the top floor. This intimate hall can host an audience of 45 visitors, and it offers panoramic views across the Julier Valley. The tower’s striking variety of form and intricate ornamentation evoke the craftsmanship of the Baroque master builders of Grisons, forging a bridge between the traditions of the past and the innovations of the future..
Research and Innovation
Tor Alva demonstrates the ground-breaking possibilities of research in computational design, digital fabrication, structural engineering and materials science. The White Tower's technical innovations include the integration of reinforcement into the 3D printing process, the use of material-saving 3D-printed structural elements, and a modular construction approach, which allows for the reuse of components. Using robotic concrete extrusion processes, concrete is only applied where it is structurally needed, thereby significantly reducing material consumption. The process no longer requires any formwork. This in turn offers new degrees of design freedom regarding expressive shapes, surface detailing, and hollow features. It enables the tower's intricate design in a novel and distinctive architectural language.
Architecture, Art, and Culture
The White Tower of Mulegns is built directly on top of the historic carriage depot. The building is conceived as a vertical enfilade composed of six distinct floors that each have their own system of ornament and offer a unique spatial experience. As visitors ascend the spiral staircase, they move through atmospherically rich spaces that range from dark, intimate chambers at the base to light-filled, airy rooms at the top. They arrive at performance space with 45 seats and a central stage, topped by an intricate dome. At dusk, the White Tower with its idiosyncratic openings appears like a lantern and becomes a lighthouse along the historic Julier Pass route.
32 Distinct 3D-printed Columns
The core design element of the tower consists of a series of 32 3D-printed columns that support the different levels of the building and define its facade. These range in form from broad and robust columns with a height of 3.4 meters on the lower floors, to slender, branching columns on the top floor, reaching 6 meters in height. The branching nature of the columns function as a truss, designed to resist lateral forces. Though the forms of these columns differ, they are unified by the consistency of the material, which visually and conceptually ties the entire structure together. The column’s bright, white concrete and undulating forms enhance the architectural play of light and shadow. The focus on columns as space-defining elements create distinct inside and outside perceptions. They are perceptible both up close, from just centimeters away, and from distant viewpoints beyond the village. In winter, the tower will be shielded from the elements by a transparent, removable membrane, providing protection from wind and snow.
Multiple Scales of Ornament
Thanks to computer-aided design and digital fabrication, each column is unique and features three distinct scales of geometric articulation. At the first scale, columns have an organic, bone-like form that helps that absorb lateral forces without additional bracing. To optimize material usage, a secondary scale of articulation is introduced, reinforcing the columns’ thin shells. This scale consists of broad, spiral waves that ascend the surface of the columns, emphasising the tower’s height. The third scale of articulation adds a unique ornamentation to each column, created by manipulating the extrusion path used in 3D printing the concrete. This material-based ornamentation directly reflects the manufacturing technique and enhances the visual complexity of the structure.
Fabrication: 3D Concrete Printing
Tor Alva demonstrates the groundbreaking potential of research in computational design, digital fabrication, structural engineering, and materials science. The innovations in these research fields will fundamentally change construction, paving the way for more sustainable building practices. For the first time, a multi-story building has been constructed using fully structural 3D-printed columns with integrated steel reinforcement. By employing robot-assisted concrete extrusion and eliminating the need for molds, concrete is precisely deposited only where needed, resulting in a 40% reduction in material consumption compared to conventional casting methods.
3D-Printed, Reinforced Concrete
In 3D concrete printing, a robotic arm successively applies thin layers of soft concrete through a nozzle. The material is soft enough to bond and form continuous, homogeneous components, yet it hardens quickly enough to support the successive layers. The printed material is based on a multi-component technology that combines white concrete with a stabilizer and an accelerator for rapid curing. This enables the creation of freeform elements with large overhangs. The 3D concrete filament used in the process is applied in layers that are 25 mm wide and 8 mm high, forming a continuous print path of approximately 5000 meters per column. Each column cross-section is composed of three filaments: the outer filament features the aforementioned ornamental texture, the middle layer contains the encasing reinforcement, and the inner filament forms hollow channels for the main vertical reinforcement.
Automatically Integrated Rebar
The key innovation of this process - pioneered by ETH's DBT group - lies in the automated integration of reinforcement during the 3D printing process Two robots work in tandem: one applies fresh concrete continuously, while the other places reinforcement between the layers of concrete. After printing the thin-walled hollow elements, longitudinal reinforcement is placed into vertical channels, which are then grouted.
Formwork-free Construction
Since the concrete is not poured in 3D printing, but rather applied in extruded strips by a robot, formwork is no longer required, in contrast to conventional concrete construction. The elimination of formwork opens up new freedoms in design with regard to expressive shapes, surface details and cavities. It also enables cost-efficient production of customized components.
Modularity and Reuse
Each load-bearing column is made up of three components — the central column, the base, and the capital. The central column is 3D printed, while capital and base are conventionally cast using 3D-printed formwork. The parts are assembled in a local prefabrication facility 10 km from the construction site, transported by truck, and then assembled on-site with a crane. With a focus on circularity and resource reuse, Tor Alva is designed as a reversible structure using only dry connections between columns. This ensures that the tower can be disassembled, relocated, and reassembled after its five-year lifespan in Mulegns, ensuring its adaptability and continued use in a new context.
Setting: The Village of Mulegns
Perched high in the Swiss Alps along the Julier Pass, the village of Mulegns has long held historical significance. Once a stagecoach stop on the route connecting central Switzerland with the Engadine region, it linked Zurich to St. Moritz. Initially a modest village, many of Mulegns' inhabitants emigrated to larger cities, working as stucateurs (plaster craftsmen) and confectioners. Successful returnees built grand villas, and as tourism began to thrive, the village enjoyed a period of prosperity.
Revitalization
Today, Mulegns faces the threat of extinction. Many buildings stand abandoned, and the population has dwindled to 16 residents. The Origen Foundation is working to preserve the village's rich cultural heritage and breathe new life into this historic place. Notably, the White Villa—now under federal protection—was recently saved through a remarkable relocation. The historic Post Hotel Löwe has been restored and is welcoming guests once again. The White Tower, standing as a beacon on the old pass road, will continue to write and reinterpret the village's history, creating a new chapter in its storied past.
Project Launch and Timeline
The White Tower project was officially launched by Fundaziun Origen on June 22nd, 2021 in Mulegns, Switzerland. The launch ceremony was attended by Swiss President Guy Parmelin, as well as the President of Graubünden Canton Mario Cavigelli and Surses Municipality President Leo Thomann.
The projected timeline for the White Tower is as follows:
| 2021 | Planning, financing and approval of the tower | |
| 2022 | Construction of a full-scale demonstration floor | |
| 2023 | Structural test of reinforced columns | |
| 2024 | January: Start of 3D fabrication | |
| November: Assembly of tower completed | ||
| 2025 | Opening of the tower and first performances | |
| 2030 | Disassembly of the tower |
Latest News
Sept. 30th, 2024: Fourth level assembled, current tower height: 26 meters
August 26th, 2024: Third level assembled, tower height: 20 meters
July 22nd, 2024: Second level of columns assembled, tower height: 15 meters
July 10th, 2024: First level of columns assembled, tower height: 12 meters
May 2024: Printing of columns completed, casting of bases, foundation in Mulegns completed.
January 2024: Begin of 3D printed fabrication of the tower at ETH in Zurich.
December 2023: Lighting tests on lowest floor of the tower.
September 2023: Stress and deformation testing of final 3D printed column designs. Columns are hollow, rebar-reinforced, and fully structural - a world first.
March 2023: Development and testing of façade systems using ETFE and various membranes. Façade can be removed during warm summer months.
| Structure: | Five levels consisting of 32 3D-printed columns | |
| Columns are reinforced and fully structural | ||
| 184 3D-printed elements in total | ||
| Dimensions: | Height: 30.0m including an existing base | |
| Diameter: 7.0m to 9.0m | ||
| Performance Space: | Capacity: 45 visitors | |
| Total height: 8.0m, covered by dome | ||
| 3D Printing: | 2500 extruded concrete layers total | |
| 8mm layer height, 25mm width | ||
| Estimated print time: 900 hours | ||
| Façade: | Removable ETFE / PVC membrane | |
| Location: | Mulegns, Switzerland; on the Julier Pass | |
- Architecture
- Prof. Dr. Benjamin Dillenburger (DBT)
- Michael Hansmeyer
- Structural Engineering
- Prof. Dr. Walter Kaufmann (CSBD)
- Building Materials
- Prof. Dr. Robert Flatt (PCBM)
- Team ETH Zurich
- Dr. Ana Anton (Research Lead), Elena Skevaki, Che Wei Lin, Ming-Yang Wang,
- Lena Kitani, Dr. Konrad Grasser (DBT); Dr. Jaime Mata Falcon,
- Dr. Alexandro Giraldo Soto, Dr. Lukas Gebhard (CSBD); Dr. Timothy Wrangler,
- Dr. Lex Reiter (PCBM).
- Project Development
- Dr. Giovanni Netzer, Nova Fundaziun Origen
- Team Nova Fundaziun Origen
- Anja Diener, Rebecca Suenderhauf, Phillip Bühler,
- Torry Trautmann, Sandro Provino
- Planning Partners
- Conzett Bronzini Partner AG - Structural Design,
- Zindel United - General Contractor
