In 1912 French postman Ferdinand Cheval finished what he had been building over 30 years and became known as Palais Ideal. It was a creation of unadulterated fantasy which showed a "strange passion that remains unarticulated."
Visually it had a strong resemblance to the similarly unquantifiable work of another oddball, Antonio Gaudi, and quickly and not surprisingly it became a pilgrimage place for the surrealists from the '30s onwards.
For them, as Andre Breton stated, the value of Palais Ideal was not in Cheval's imagination but the mere realisation by which "dreams had become a reality."
Enter, 20 or so years later, the Situationalist International, an ephemeral, intuitive and largely theoretical response to capitalist urban solutions.
French poet Arthur Rimbaud cited Guy Debord as its most influential figure. "Il faut changer la vie" - we must change life. It was an injunction that was to inform all Situationist International challenges to the prevailing order.
In post-World War II France there were over four million displaced people. More than a million people arrived in Paris between 1945 and 1960 and 46 per cent of Parisians were new to the city.
One in 10 were not French and most were working-class people from north Africa, Spain and Portugal.
In a return of Haussmann's mid-19th century policies of forcible displacing of the restive working class to the periphery of the city, repetitive banal architecture was devised in a "spatial strategy of class segregation."
The organic arteries to Paris were severed as vertical and horizontal slabs littered the outer cityscape in a arrangement that intentionally segregated, disenfranchised, marginalised and ultimately alienated.
Capitalism was looking after its own class by creating a more sympathetic environment for the bourgeoisie.
For a while, the Situationist International rehearsed concrete ideas of new urbanism, "psychogeographicly" transforming the cartography of Paris employing a mixture of aerial photography and art in which psychology played as privileged a role as topography.
The ideas of Situationist International Dutch member Constant, such as the Orange Construction - a special floating structure that could be transformed at will by its inhabitants in line with Situationist International participatory perpetual mobile of self-discovery and affirmation - were entirely socialist in their intention.
The Situationists also looked to history and studied the Paris Commune in great detail, defining it as a "liberation from the miseries and humiliations of everyday life and the rebirth of the fete" - an expression of revolutionary urbanism that did change life, if only for a short period of time.
In 1965, they were offered an event that would match the Commune's intensity and sense of purpose - the Watts riots in Los Angeles.
Situationist International identified "the eminent rationality of the rioters" and their actions as "constructive appropriation of capitalist space."
At that time architecture, as the Situationist International's central concern, was fading away and three years later its concept of a liberating urban revolution and festival rolled into one were spectacularly embodied in the 1968 Parisian uprisings.
The innovatory theoretical concerns of the Situationists should inform our struggles today. They pushed the boundaries of the imaginable to the limit and encouraged dreaming, without which revolutions become dull and soulless.
A book on the movement titled The Situationists And The City, edited by Tom McDonough, is out now on Verso, price £14.99.