This stunning solar-powered Roman convention centre hides a building within a building

Known simply as 'the cloud', the five-level complex includes a high-rise hotel, a 1,760-capacity hall and is the largest building to be erected in Rome for more than 50 years

Its creators christened it "the floating space" but in Rome everybody knows it as "the cloud". The New Congress Centre opened in October 2016 after eight years of work, filling 55,000 square metres in the EUR business district in the south of the city. Designed by Roman husband-and-wife practice Studio Fuksas, the building contains another building inside it: a cloud-shaped auditorium floating in a steel-and-glass "theca".

"It's a rigid, geometric element and the cloud is its polar opposite," explains architect Massimiliano Fuksas. "The perception of the spaces between the theca and the cloud changes depending on the observer's point of view." The cloud's steel framework is shrouded by 15,000 square metres of glass fibre and silicone, a fabric that helps disperse and amplify light throughout the building.

The five-level complex, which includes a 400-room high-rise hotel and a 1,760-capacity hall, is the largest building to be erected in Rome for more than 50 years, and 73-year-old Fuksas and his wife Doriana worked to whittle its environmental impact down to a minimum. The building's cooling system taps into the waters of a nearby artificial lake, and rooftop solar panels produce electricity while shading the building's interior from intense sunlight.

"Apart from being environmentally compatible, the building has also been designed to behave optimally if a seismic event occurs," Fuksas says. This is key in a country that has suffered recurrent quakes over the past few years.

The building's base isolations are horizontally stiff but vertically flexible, meaning it will stand still during a small or medium quake, and oscillate without falling apart during a more intense event. "The cloud is chaos trapped inside rationality," adds Fuksas. Architect-speak for a safe place to shelter.

This article was originally published by WIRED UK