„The pebble of Budapest” – How BEMO wrote architectural history with the Budapest Sports Arena

A gray December day in 1999. The flames that engulf Budapest’s old sports arena leave more than just a building behind – they leave a gap in urban memory.  However, in 2002, the ashes were not simply transformed into a new building, but a technological milestone for BEMO: it was the very first project in which the MONRO® system developed by BEMO was used.

Inspired by the natural, smoothly polished stones of the Danube riverbank, KÖZTI Architects designed  a building that broke new ground not only in form but also in terms of construction. A design that could hardly be realized with conventional means. For us at BEMO, this was the perfect challenge – and the birth of MONRO.® The goal: a 26,000m² building envelope made of aluminium standing seam profiles that nestles seamlessly against the complex, double-curved free-form geometry. The whole thing was then to be completed in just 18 months of construction.

The public christened the building „The Pebble” – and not without reason. The almost 41,000 m² large, silvery gleaming building with its aerodynamically curved, metallic outer skin looks as if it has been sanded by water. The paint – „AluNatur Titanium Brushed” – was produced especially for the arena.

The sports arena impresses not only with its iconic shape, but also with a complex architectural composition consisting of three essential elements :

• The arena itself – a 200,000-ton, streamlined body, anchored six meters below the square level and accessible via bridges.
• The raised forecourt, which lifts the building out of the urban structure on a plinth, separates traffic flows and creates space for staying.
• The „crystals”, which stand in stark contrast to the soft shape of the arena and house cafés, shops or exhibitions.

This clear separation of functional levels, connected by ramps, stairs and elevators, creates not only a functional logic, but also an impressive spatial dramaturgy – perfectly staged by the architectural design language.

For us at BEMO, this project became the blueprint for a new architectural-technological collaboration. The organic, double-curved aluminium outer skin of around 26,000 m² required a production system that did not exist before.

For the first time, our patented BEMO-MONRO® system was  used – a roll forming technology that can be used to bend and shape standing seam profiles individually. The highlight: The rollers of the roll forming and crowning machines are individually infinitely adjustable, computer-controlled and thus enable freely definable shapes, radii and curvatures. Until now, such profiles could only be realized by means of cost-intensive special procedures.

Despite the high production speed, the profiling and shaping of the aluminum sheets is carried out evenly and gradually to avoid the risk of cracks and other defects, especially compared to traditional bending processes or pressing metals.

The principle behind it: File to Factory. The shape of each individual N65 standing seam sheet of the Budapest Arena, which is up to 21 meters long, was determined on the basis of the 3D model and transferred directly to the production machines. They manufactured the components directly on site. Despite the complexity of the free-form membranes, only a few fitters were needed to lay a component.

The result is a building whose shiny metallic shell appears to be made of one piece from the lowest point to the top. Ribbon windows, technical equipment and openings elegantly disappear behind slats that adapt exactly to the shape of the building. The glazed main entrance, on the other hand, is carved out of the streamlined body like a gaping mouth – during the day it reflects the sunlight, at night it becomes a light source itself. Architecture and material merge into a single unit in which every track, every curvature, every line has been digitally planned in advance and then precisely manufactured.

This seamless combination of design, planning and production not only defined new standards  in the free-form architecture of metallic building envelopes. It made the seemingly impossible plannable, feasible, mountable – the only limitation in the design of the profiles is one’s own imagination.

Today, the BEMO MONRO® system is used worldwide in innovative architectural projects. But it all started in Budapest – our first project, which set standards with a roof curved in two directions and an outer shell that looks like a „polished pebble”.

This project showed us that MONRO® can be used to implement even the boldest architectural visions. The findings from Budapest flowed directly into the further development of our system, which is now used internationally in demanding free-form projects.

The new Budapest Sports Arena impressively demonstrates what is possible when design vision, digital competence, technological innovation and experienced BEMO employees   come together. What began as a pebble is now a rock in the landscape of modern architecture: technically brilliant, formally powerful.

The project is not only a reference object for us. It is the place where we broke new ground with MONRO®. And it remains a symbol of how much creative freedom is created when technology is understood not as a limit, but as an opportunity to realize visionary architecture.