For the second year running, Copenhagen was named the world's most livable city in the 2026 Economist Intelligence Unit's Global Liveability Index. According to the Danish Architecture Center, part of this progress in urban quality of life is due to the work of Danish architect and urban planner Jan Gehl, who celebrates his 90th birthday this year. Jan Gehl has dedicated his professional career to the field of city life and people-centered urban development, founding Gehl Architects (now Gehl Studio) in 2000 and publishing extensively on urban design methodologies to create lively, healthy, and human-centric urban environments. In honor of his birthday, the Danish Architecture Center is presenting an exhibition and a series of activities centered on the role he has played in urban development worldwide.

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There are two main reasons why boat windows are round. They are easier to seal and, above all, more resistant to the high pressure that water exerts on them. This is because living corners are places where tensions are naturally concentrated, weakening the structure as a whole. This is also why aircraft windows are small and round; high pressures are better distributed in curved shapes, reducing the likelihood of cracks or breaks.

In architecture, circular openings are quite old. The Oculus, a type of circular window, has been a feature of classical architecture since the 16th century. Also known by the French expression oeil de boeuf (bull's eye), circular or semi-circular openings are formed from the construction of masonry arches, which allow for the creation of openings only by locking the constitutive pieces. Over time and following the incorporation of new technologies and development of construction knowledge, creating rectangular openings in buildings has become easier, more efficient, and cheaper than creating round ones. However, these circular windows still continue to figure in a multitude of projects.

With the extensive list of acclaimed alumni of his firm, OMA, it is not a stretch to call Rem Koolhaas (born 17 November 1944) the godfather of contemporary architecture. Equal parts theorist and designer, over his 40-year career Koolhaas has revolutionized the way architects look at program and interaction of space, and today continues to design buildings that push the capabilities of architecture to new places.

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This article was originally published on November 13, 2013. To read the stories behind other celebrated architecture projects, visit our AD Classics section.

Much of the spatial composition of the Villa dall'Ava was influenced by its site, in a garden on a hill. It was completed in 1991 in the residential area of Saint-Cloud, overlooking Paris. The clients selected OMA to design a house with two distinct apartments—one for themselves and another for their daughter—and requested a swimming pool on the roof with a view of the Eiffel Tower.

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The fourteenth of July is Bastille Day, a day that commemorates the start of the French Revolution. Named for the fortress prison that was stormed by revolutionaries on July 14^th, 1789, Bastille Day is celebrated globally both by France and her former colonies, as well as many cities in the US. In honor of this historic date, we’ve compiled some of our favorite French projects from the past few years. In this round up you’ll find classics such as the Villa dall’Ava by OMA, as well as fantastic works like Nova Green by Agence Bernard Bühler, Pontivy Media Library and Louviers Music school by Opus 5 architectes, Platform Architecture’s Aquitanis Headquarters, L’Atoll Angers by Antonio Virga Architecte and AAVP Architecture, a Parking Attendant’s Pavilion by Jean-Luc Fugier, Kengo Kuma’s Aix en Provence Conservatory of Music, and Origami by Manuelle Gautrand Architecture. Joyeux quatorze juillet!

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