Milan may be Italy’s fashion capital proper and home to its seasonal catwalk shows, but Rome is the city of choice for one-of-a-kind, fabulous fashion blockbusters. Fendi proved that theory true last night in a multi-venue event spectacular that had models literally walking on the water of the sparkling Trevi Fountain and ended with moonlit dancing in Rome’s lush Villa Borghese.

The evening began at the Accademia di San Luca with a cocktail and the reveal of Fendi Roma, a new Assouline book that traces the Roman brand’s 90 year history in photos and illustrations, as well as its fruitful 50 year collaboration with Karl Lagerfeld.

Five-hundred guests then moved by foot to the Trevi Fountain, which after three years of laborious restoration funded by Fendi was finally unveiled as its former gleaming, glorious immaculate marble self. A plexiglass runway had been constructed just inches above the emerald green water which allowed the models — all clad in Karl Lagerfeld’s wizardly haute couture creations – to walk beguilingly across its surface.

The fashion was as lofty and beautiful as the location, Lagerfeld painting his meticulously made garments with intricate fur intarsias and embroideries that showed landscapes and romantic fairy-tale scenes. Incredulously all made from fur, the clothes were both light as air as well as ornately complicated, true mini masterpieces that showed the wonder of what Fendi’s artisans can actually do.

Later, guests were shuttled up to the Terrazza del Pincio, where 600 seats had been set under an open sky, a crescent of sculptural pine trees planted by Mussolini, miniature fountains recreated for the night in honour of the evening’s theme and a spectacular light installation designed by Paul Cocksedge at the entryway.

With a view over St Peter’s in the distance, Fendi CEO Pietro Beccari gave a proud speech, admitting that authorisation for the fountain’s use had occurred at just 1am the night before. His beaming French boss, LVMH’s Bernard Arnault, didn’t seem to mind. Kate Hudson, meanwhile, grabbed the mic and introduced performer Giorgio Moroder. The dancing began under the stars, and then moved to the Raspoutine nightclub.

The following morning, Fendi inaugurated 'Fendi Roma: the Artisans of Dreams', its first major exhibition at the Palazzo della Civilità Italiana. As Lagerfeld rightly put to his boss Beccari, after the mega fest: 'What on earth are we going to do in 10 years time?'