The moment a new museum opens, it goes from being an ambitious concept to a multi-purpose institution rooted in time and space. But what about the museums that are conceived but never achieved? To what degree do they exist as architectural works, and what is their enduring value?

These are among the questions that surface in a new exhibition, 'Musées à Venir' ('Museums to Come') at Azzedine Alaïa’s gallery space in the Marais. If the premise seems philosophically open-ended, this particular show proves as precise as the master designer’s tailoring, in part because just two architects are represented: Jean Nouvel and Claude Parent. A generation apart, the former worked under the latter in the late 1960s, and they have intersected each other’s lives ever since. In fact, it was over lunch chez Alaïa in June 2014, that the idea took shape.

As academic and gallery consultant Donatien Grau suggests, the juxtaposition exists as a conversation that can be interpreted on several levels: theoretically, personally, aesthetically. Four works from each are featured, including their separate proposals for the Plateau Beaubourg, 1971 – better known today as the Centre Pompidou. And yet, the architects’ projects are grouped separately on alternating walls versus side-by-side, maintaining deliberate distance like a show of respect.

'They are two very senior architects and on the one hand, it would have been too obvious,' Grau says, of opting against pairing the presentation. 'Both Jean Nouvel and Claude Parent believe deeply in the idea of intelligence – getting you to do a little bit of work. And what is a conversation might have appeared to be a confrontation.'

Still, comparison is inevitable, principally as a function of methodology. Parent’s dynamic drawings for the Nouveau Musée, an unpublished work featured for the first time, testify to the enormous challenge of communicating spatial criteria and visitor flow in two dimensions. Nouvel’s plans for the Musée Lascaux-IV , 2012, and the Guggenheim in Guadalajara, 2005, benefit from computer-assisted design and project a sharper sense of orientation. Where Parent’s text is clipped and aphoristic – 'In the world today, we cannot forget color, just as we cannot forget the black of night and the grey sky' – Nouvel takes an explanatory, narrative approach.

For even more perspective, the book accompanying the exhibition includes works contributed by Marc Newson, Anish Kapoor, Alejandro Jodorowsky, Adel Abdessemed and others—each partnered up to a project to underscore how Parent and Nouvel’s influence prompt new points of departure.   

On the evening of the vernissage, shortly before the arrival of Parent (now 92), Renzo Piano and French culture minister Fleur Pellerin, Nouvel admits that these projects never lose their significance. They serve as the missing links between the realised achievements, a vision that nonetheless responds to a challenge. 'We can consider that the conditions of these projects enlighten perhaps the things that will often happen after,' he tells Wallpaper*. Which is to stay, an unrealised state isn’t a failed state. Rather, these are museums that become timeless, says Nouvel, 'out of necessity'.