Most of the places where we live are obstinately, resolutely earth bound: think of maundering suburbs, the plate-glass high rises of financial centres, the re-gentrified areas of inner cities. None of these suggest anything other than themselves: places where people live, sealed off from heaven above and oblivious of hell below. But there are a few places where the places of this world are suggestive of and open to the worlds above and below. Most of these are natural places, thin places where the boundaries are ill defined, but there are a few that are man made, and none more so than the city that is the subject of this wonderful history: Venice.

Even now, living off its beauty, with most Venetians reduced to living on the mainland in Venezia Mestre, Venice is not like anywhere else on earth. It has always been so, as Crowley ably tells in this book. People, outsiders, have always looked at Venice and wondered, how could it exist? A city without land, without anything in the way of natural resources, and yet for centuries it was the node of the Mediterranean, the eye at the centre of a virtual empire that tied together with the invisible thread of trade and money a state that stretched over the shifting miles of sea and penetrated deep into the trade routes that linked Christendom, the Islamic world and beyond. Venice, built on water, lived on money and sold itself as a dream.

Today, the dream lingers, and the wanderer, turning a corner into a quiet piazza or a still canal, can never entirely escape the feeling that the next turn might take him over an invisible boundary and into another Venice, one that still draws to itself all the trades of the unseen worlds, and sends them out again into all the different realms. Ghosts walk quietly alongside the water, heard in the slap of wavelet on quay and the drift of wind over the lagoon. Walk here and you walk among multitudes unseen.

One day, I will go back. I’m not sure if I will return.