Marco Polo, the narrator of Italo Calvino's Invisible Cities, does not attempt to describe the city of Zaira by simply listing the number of steps in its streets that rise like stairways, or the precise type of zinc tiles used on its roofs. He knows that mere facts alone are not sufficient. For Zaira, like all great cities, consists of "relationships between the measurements of its space and the events of its past". Monuments, city squares, even street names are dense with memories and recollections: the city is a place of living history, a mashup of past and present.

Like Calvino's lyrical novel, this evocative collection of "city symphonies" attempts to go beyond facticity in order to capture the intangible essence of city life. It is a bold and admirable ambition, and generally these riffs on the urban everyday rise to the occasion. Highlights include Kasia Boddy on the history of attempts to green the city by growing pot plants on window sills, Michael Newton on the lodger  a "new urban character" in 20th-century film and fiction  and Geoff Dyer's delightful account of his love for familiar urban places and routes: "wherever we live we are always compelled to repeat the same thing over and over". Each writer contributes a piece to the jigsaw that is daily life in the modern city  a seemingly mundane subject, yet one that is shot through with the miraculous, like Ben Wilson's gemlike acrylic paintings on discarded chewing gum stamped into the pavement, described in Esther Leslie's piece on "Recycling".

The editors describe the attempt to define urban life as akin to diagnosing some pervasive malady or "a state of delirium so habitual as to be almost unnoticeable". It was while recovering from an illness that Giorgio de Chirico was inspired to paint the hauntingly beautiful series of metaphysical cityscapes that began with Enigma of an Autumn Afternoon (1910). Sitting in the Piazza Santa Croce in Florence, watching the world pass by, de Chirico had an epiphany in which he saw the city as if "for the first time". The city itself seemed, he recalled enigmatically, to be "convalescent". This experience prompts Beaumont to outline a poetics of urban convalescence. The classic literary example is Edgar Allan Poe's wonderfully strange story "The Man of the Crowd" (1840). Restored to health after an illness, the narrator is sitting in a London coffee house engaged in that essential urban pastime  people watching. But among the crowd he catches sight of someone who embodies "the type and the genius of deep crime" and gives chase, following the man for hours on end through the metropolis that had become the largest city on the planet. For Beaumont, it is the convalescent's state of "unpredictable, half-repressed euphoria" that allows him or her to see the city as if for the first time: "the whole world is made strange, made new".

The idea that the city can be the site of potentially transformative experiences is a recurring theme in these essays. Gregory Dart examines the origin of daydreaming "as a metropolitan pastime" in the first half of the 19th century. He sees a parallel between Thomas de Quincey's laudanum-fuelled nighttime wanderings around London, during which he discovered what he called "terra incognitae", and the surrealists' celebration of Paris's chaotic and run-down shopping arcades. Both viewed the city as a place of "fantasy, reverie, daydream", and in the commercial city, where the drug of choice is profit, these are subversive modes. Such ideas inspired the situationists, for whom the city was far more than a mere centre of wealth creation. For them, the ideal city would be a crucible of creativity, a place of liberation rather than bondage.

Sadly, the reality often falls short of the ideal. Inspired by last year's swine flu outbreak, Iain Sinclair contemplates the "Viral City", a bleak, Ballardian environment of "hollow retail glaciers" and "tapering towers", choked by exhaust fumes and governed by "celebrity mayors" and "spivvish Etonian politicians". In this wonderfully doomy concoction, Sinclair shifts from global plagues to media contagion in the "Vir(tu)al City": "don't touch those tabloids!". As cities throughout the developing world grow and metastasise, the urban future increasingly resembles the source of the swine flu outbreak: Mexico City, "an infinitely extended urban organism, El Monstruo". For world cities in the age of global capital, a pandemic of homogeneity and artificiality threatens: "When anywhere is everywhere, only the familiar is familiar. If you can't find the postcard, you haven't arrived."

As Calvino's narrator suggests, the city of memories is one antidote to urban non-places, creating enduring resonances between citizens through time and space. To tap into the history of a street or a building is to experience an extra dimension, as Michael Sheringham's rich and allusive essay on the city as archive makes clear. We live on top of our urban ancestors. At the Museum of London, the display on Roman Londinium notes that archaeologists have to dig down through six metres of debris to reach the remains of the 2,000-year-old city. All that is left of the world's first cities  in today's Iraq  are mounds (or "tells" in Arabic) of compacted history: artificial hills in a now uninhabited desert. They are poignant reminders that all cities one day end as ruins, a subject movingly explored in Marshall Berman's essay about the South Bronx, where he grew up.

In living cities there are also layers of history, for as the great chronicler of the city Lewis Mumford notes, "the city unites times past, times present, and times to come". According to Sheringham, "the city is a memory machine", and a walk through its streets can open the files in this archive, setting free the ghosts of memory associated with the structures and spaces. Urban fiction provides Sheringham with some marvellous examples, ranging from Les Misérables by Victor Hugo (an "urban archaeologist"), to WG Sebald's Austerlitz, in which buildings are described as "the materialisation of mental landscapes".

Rousseau said that "houses make a town, but citizens make a city". The city is, however, far more than even its present inhabitants: it is a repository of living memories, of history both on an intimate and a grand scale. All you need is the right key to unlock them.

PD Smith is writing a history of cities for Bloomsbury.