After working abroad for six years, young engineer Christen Ostenfeld returned to his hometown of Copenhagen in 1930. Full of creative energy, the 29-year old established his business in a small apartment in Copenhagen's infamous Vesterbro neighbourhood and went straight to work. 

Just a stone's throw from the office, Ostenfeld's first major assignment was a comprehensive renovation of the run-down Scala theatre.

Above: This is a photo of the original National-Scala, Scandinavia's largest entertainment venue at the time.

National-Scala, 1931

With a short deadline, Ostenfeld had to work fast. He introduced prefabricated steel structures which allowed the contractors to keep up the pace, even in the cold Danish winter. One year later, in 1931, the official opening of the National-Scala took place with 2,000 guests, dressed to impress.

Ostenfeld was an immediate success – and he was determined not to rest on his laurels.

Above: Ostenfeld designed the 150-meter long Aggersund Bridge, spanning the Limfjord. The bridge was inaugurated in 1942 as the first major Danish bridge designed by a private engineering consultancy

Ostenfeld went on to engineer some of Denmark's most iconic buildings of the 1930s, including the Aggersund Bridge in Northern Denmark (1938) and K.B. Hallen in Copenhagen (1937). 

K.B. Hallen, 1937

When it opened in 1938, it was Europe's largest private sports complex, with seats for 5,000 spectators. But it was rock 'n' roll that put K.B. Hallen on the map: in 1964, the venue hosted the first and only concert in Denmark by The Beatles. The Rolling Stones, B.B. King, Jimi Hendrix and Miles Davis also played there. 

Gentofte badminton hal

Gentofte Badminton Klub, a sports club in the suburbs of northern Copenhagen, moved in to its current badminton hall in 1936. Christen Ostenfeld's young engineering firm designed the project – and Ostenfeld himself stopped by to celebrate the inauguration of the building.

After the war

In 1946, Wriborg W. Jønson became a full partner and the company – which now had 25 employees – changed its name to "Chr. Ostenfeld & W. Jønson, Rådgivende Ingeniører" (in short, Ostenfeld & Jønson). 

Ostenfeld had just designed a cylindrical tank for liquids and granulated materials, using prestressed concrete. This was the first example of what would later become the world-renowned Ostenfeld Silo.

The Ostenfeld Silo

The Ostenfeld Silo set itself apart from the rest. Despite the silo's huge dimensions, the walls were just 25 cm thick, making it significantly cheaper to build. Being prestressed, the walls could still bear the pressure from within and remain sealed.

Boom time - the 50s and 60s

Above: The suspension bridge at Uittamo in Finland, 1960, was an important technical breakthrough for Ostenfeld & Jønson.

Prestressed concrete turned out to be useful for more than just silos. The dynamic duo, Ostenfeld & Jønson – and their now 50-strong staff – became Scandinavia's undisputed favourite consulting firm in the construction game. With new offices in Paris and Ghana, the company went global and won new contracts all over the world. Ostenfeld & Jønson engineered tunnels, tram depots, cotton mills, concrete tanks for boiling laundry water, wastewater treatment plants and countless swimming baths and bridges.

Above: The Little Belt Bridge is a 6-lane suspension bridge with a main span of 600 m. Opened in 1970; the bridge links Funen with Jutland.

The New Little Belt Bridge

In 1960, two suspension bridges at Uittamo and Pargas in Finland marked a breakthrough for the firm's bridge building division. These bridges shaped the design for a new motorway bridge across the Little Belt in Denmark, the New Little Belt Bridge.

The pylon legs rise 121 m above sea level. At 70,000 tonnes each, the two buried anchor blocks, with their wing-shaped bottom slabs, resist 17,000 tonnes of force from the main cables.

COWI delivered the conceptual design, site investigations, tender documents, detailed design, administration and supervision. For an old school, jazzy and highly detailed 'podcast' about the bridge, listen to or download the narration track for the film, The Motorway over the Little Belt from 1970.

Global engineering - 70s to millennium

Above: View of the Kuryanovo wastewater treatment plant in Moscow, which COWI designed from 1992.

Chr. Ostenfeld & W. Jønson became COWIconsult when Christen Ostenfeld retired in 1972. 

By 1979, the company had more than 800 employees, generating a third of its turnover abroad. Moving in to new markets, the company won major assignments in Africa, the Middle East and, later on, the former Soviet Bloc. 

With the fall of the Iron Curtain, the company established offices in Moscow, Latvia, Hungary, and Lithuania.
The company collaborated with the World Bank and the United Nations Development Programme on projects in developing countries. The company also engineered several large-scale projects, like The Great Belt Bridge (1998) and the Copenhagen Metro (1994).

The earliest design for The Great Belt Bridge was in 1936, and up until the construction of the final bridge in 1998 it had changed many times. Watch video to see how the bridge has been imagined over the years.


In 2016, Copenhagen's driverless metro system carried 62 million passengers.

Voted the world´s best metro, COWI was responsible for the overall design coordination of the 21 km network and its 22 stations. This work included the supervision of works on tunnels, stations, emergency shafts and the mitigation procedure against potential damage to neighbouring buildings.

The NEW M3+M4 City Circle Line, including 17 new stations, is scheduled to open in 2019. Read more about Copenhagen Metro. 


2000s to today

In 2002 COWI acquired Kampsax and Interconsult, two major Scandinavian consulting companies. These acquisitions doubled the number of staff, making COWI a leading consulting company in northern Europe and parts of Central and Eastern Europe.

COWI consolidated this position by acquiring Swedish company Flygfältsbyrån in 2009 and leading UK tunnel and underground engineering consultants Donaldson Associates Ltd in 2014.

Since the Millennium, COWI has engineered a long suite of large-scale projects, including the Tanzam Highway in Tanzania (2005), the London Array (2009) and the Doha Metro in Qatar (2013). Every year, we are involved in more than 14,000 projects across the globe.

In November 2018, COWI acquired Denmark's largest architectural practice, Arkitema - COWI's biggest ever acquisition. Arkitema is specialised in housing, urban design, office buildings, health and educational buildings. Amongst others it is known for the Sluseholmen, an artificial peninsula in the southern part of the Port of Copenhagen, Denmark.

COWI has continued to be part of the world’s elite in a number of selected specialist areas within engineering, economics and environmental science. In 2017, Engineering News-Record ranked COWI 1st in solid waste, 3rd in bridge consultancy and 4th in harbour and marine structures. 

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