Tor Alva: 30 m modular 3D‑printed concrete tower for reuse

Tor Alva: A 30-Meter, Four-Storey Modular 3D‑Printed Tower in Mulegns

The world’s tallest 3D‑printed concrete tower stands in a high Alpine setting, where Tor Alva rises to a height of 30 meters, including its base. Unveiled on 20 May 2025, the four‑storey structure is designed for disassembly and reuse, with guided tours starting 23 May 2025 and staged performances planned from July 2025. The project is positioned to remain in Mulegns for about five years before its components could be removed and re‑erected elsewhere, aligning with circular construction ideas.

The site is in Mulegns, Switzerland, on the Julier Pass in the Swiss Alps. It is described as the world’s tallest 3D‑printed concrete tower, a title earned through a modular design that uses coordinated robotic reinforcement and a printing process that eliminates traditional formwork. The tower’s interior includes vertical stairs and a vaulted concert venue on the top floor, offering panoramic views across the Julier valley, while the exterior presents a windowless façade with a criss‑cross pattern that reflects the printing method.

Nova Fundaziun Origen commissioned Tor Alva, with project designers Benjamin Dillenburger and Michael Hansmeyer at the helm. ETH Zurich led the research and development across several groups and institutes, working within the National Competence Center Digital Fabrication framework. The project received support from the ETH Foundation and backing from the Surses community, along with private donors, positioning the effort as a collaborative, interdisciplinary experiment in digital fabrication, architecture, and materials science.

The project brought together ETH Zurich’s Digital Building Technologies group, the Institute of Structural Analysis and Design (CSBD), and the Institute of Building Materials (PCBM), among others. The endeavor was complemented by collaboration with ETH spin‑offs Mesh and Saeki, and it involved industry partners such as Sika, BASF, and Knauf. The aim was to explore a fully robotic, print‑driven construction workflow that could support complex geometry, built‑in reinforcement, and quick production while enabling component reuse at the end of a lifecycle.

The tower is modular in design, with components that can be disassembled and relocated. It uses dry connections and removable screws instead of adhesives, a reinforcement strategy that blends horizontal steel rings printed into the structure with vertical rods added after printing. The rod cavities are filled with self‑compacting mortar, and the upper sections incorporate prestressed rods to boost crack resistance. Stainless steel is used in place of traditional rebar to improve durability, and initiatives to accelerate carbonation of the concrete aim to reabsorb atmospheric CO₂ over time. While the specialized concrete mix brings environmental considerations, the team has taken steps to reduce environmental impact through reuse, corrosion resistance, and carbon‑related strategies.

Printing at Zurich’s ETH facilities began early in the project, with the first eight columns of the lower floor printed by a robot at ETH Zurich. The columns were assembled on site in May 2024, marking a major milestone in a process that uses thin, layered extrusion of soft concrete to form hollow, load‑bearing columns. The exterior’s windowless façade features a criss‑cross pattern that highlights the layered character of the 3D printing process. The work relied on two robots: one arm extruded concrete layer by layer, while a second robot placed reinforcement between layers. The printing process required no traditional formwork, and the concrete mix was developed to bond across layers while hardening quickly enough to support successive layers.

Parametric scripting played a crucial role, generating a digital model that could be adjusted, visualized, and simulated within the limits of robotic printing. The result is a set of branching, twisting hollow columns that guide interior spaces, including a top‑floor concert venue. The interior’s stairs and rooms are arranged around these columns, creating abstract and atmospheric spaces. The printed columns form joint‑based, hollow structures whose geometry supports both aesthetics and function, including a vaulted venue for performances and a panoramic vantage point for visitors.

Tor Alva’s narrative frames the tower as more than a building; it is an installative architecture intended for art installations, music, and theater performances. The project highlights reuse and circularity, with modular components designed to be disassembled, relocated, and reassembled elsewhere. The tower’s five‑year on‑site presence in Mulegns is intended to be a bridge between technology, culture, and community, offering a venue while proving a proof‑of‑concept for future digitally fabricated, relocatable architecture.

Frequently Asked Questions

Key features table