Towering Achievement: ETH Zurich Completes World’s Tallest 3D-Printed Concrete Structure

ETH Zurich has completed a groundbreaking project in Mulegns, Switzerland: the world’s tallest 3D-printed concrete tower, Tor Alva. Standing at 30 meters and rising over four stories, the structure marks a significant milestone in the application of robotic construction techniques. 

Unlike traditional cast-in-place concrete, Tor Alva consists of 232 printed elements fabricated using a two-robot system. One robot extruded a specially formulated concrete in layers while the other inserted reinforcement rings at 20-centimeter intervals. Vertical reinforcement bars were added after printing, and prestressed rods were used in the upper section for improved structural performance.

The concrete was engineered to balance fluidity and rapid hardening, supported by additives that enabled complex geometries. A hybrid reinforcement method was applied, combining horizontal rings with post-installed vertical steel bars filled with self-compacting mortar. All components were designed using parametric modeling and printed over five months on the ETH Hönggerberg campus before being transported and assembled in Mulegns.

The key structural and fabrication specifications of Tor Alva are:

• Structural Composition:
  Tor Alva stands as a four-story structure, supported by a total of 48 load-bearing columns. Each floor incorporates a combination of double and quadruple columns, 8 of each per level, while the double dome crowning the tower features an additional 8 triple and 8 single columns. All columns include fully integrated reinforcement.

• 3D Printing Parameters:
  The tower was constructed using approximately 2,500 layers of 3D printed concrete. Each layer measures 8 millimeters in height and 25 millimeters in depth. The total printing process required around 500 hours to complete.

• Component Breakdown:
  The assembly consists of 232 unique 3D printed concrete elements, supplemented by 104 prefabricated components produced using printed formwork. This hybrid approach allowed for both design flexibility and manufacturing efficiency.

• Overall Dimensions:
  Tor Alva reaches a total height of 30 meters, including its base, with a diameter varying between 7 and 9 meters across its vertical profile.

This Swiss innovation reflects a wider adoption of 3D printing in civil engineering projects worldwide. In Tanzania, an international firm completed a 3D-printed community center at Hope Village using local earth. This facility supports education, housing, and childcare, reinforcing the technology’s relevance in underserved areas.

Simultaneously, at the 2025 Venice Biennale of Architecture, modular rooftop living units called Tiny Penthouses were proposed to address housing shortages. Designed to be installed on existing buildings, these units utilize digital fabrication and promote vertical urban growth without extensive redevelopment.

All these efforts demonstrate the expanding role of 3D printing in delivering sustainable and context-sensitive construction solutions.

Following, a video showcasing the remarkable characteristics and construction process of the Tor Alva Tower.