The land chosen for the Russian Orthodox Spiritual & Cultural Centre project in Paris was originally occupied by the former headquarters of Meteo France. It is close to a number of very popular Parisian tourist attractions and it is adjacent to the banks of the River Seine. The development adjoins the Palais de l’Alma and is not far from the Eiffel Tower, the Quai Branly museum, the Invalides Esplanade on the left bank, and the Grand Palais and the Museum of Modern Art on the right bank. The development consists of four separate entities, each with its own distinctive identity but forming a harmonious ensemble in which buildings resonate with one another and with their immediate environment.

The property development consists of: - A cultural centre (the Branly building), including a book shop, exhibition spaces and a cafeteria. - A Russian Orthodox cathedral. - A parish centre (the Rapp building), including a 200-seat auditorium and foyer, offices of the cultural service of the Russian Federation Embassy in France and furnished apartments. - A Franco-Russian primary school for 150 children (the Université building), including classrooms and workshops, an infirmary, a canteen and kitchen, six apartments for teachers and indoor and outdoor play areas.

THE DOMES OF AN ORTHODOX CATHEDRAL Onion domes are characteristic of Russian religious architecture. Although the number can vary, there are generally five of them, as there will be on the future Holy Trinity Cathedral under construction on Quai Branly in Paris. The large central dome and the four smaller ones symbolise Christ and the four evangelists, Matthew, Mark, Luke and John.

A WORLD FIRST Traditionally, onion domes consist of a timber or metal framework covered with leaves of gilded copper, slate or ceramic. For the Holy Trinity Cathedral, architect JeanMichel Wilmotte wanted to create totally smooth domes, a finish that is difficult to produce using traditional techniques. The domes of Russian Orthodox cathedrals are generally multi-faceted because they consist of an assembly of hundreds of copper sheets.

In order to give full force to Wilmotte & Associés’ architectural project, Bouygues Bâtiment Ile-deFrance decided to use composite materials. Widely used in the aviation and shipbuilding industries, composite materials are virtually absent from the construction sector. The use of this technology to create the cathedral’s domes is a world first. Prototypes produced in partnership avec Multiplast, a company based in Vannes which constructs racing multihulls around the world, immediately convinced Jean-Michel Wilmotte in terms of the technology and the architectural rendering. Additionally, this technique reduces the weight of the domes. The central dome would have weighed 42 tonnes using traditional materials, but with the use of composite materials it weighs only 8 tonnes. It also shortens construction time, because the domes can be prefabricated as the structural works are being executed.

A 9-MONTH MANUFACTURING PROCESS The process of producing the five domes began in June 2015. The large central dome consists of 8 lower petals, 4 upper petals and a top cone that supports the cross. Initially, the casts for each of these elements had to be manufactured. To produce a petal, three thicknesses of glass fibre are placed in the cast, then thermoplastic foam 50 mm thick and finally three more thicknesses of glass fibre. The whole thing is placed under vacuum before epoxy resin, which will spread over all the fibres, is injected. The technique is known as infusion. After curing, the cast is struck from the petal, which can then be prepared for gilding. The petals are assembled In the workshop to check the fit, and then they are gilded. Once the gilding of all the elements is complete, each dome is dismantled and transported in a special convoy to the Paris construction site, where it is reassembled at ground level.