It is a truism that a skilled architectural photographer can give glamour to the least likely subject. Hence the photographs that usually appear in architectural magazines are only partial guides to the look of the built world, the more so because they tend to isolate buildings rather than portray them in context. The images in Open City are different.
The exhibition features the work of 19 photographers from the past 50 years. Its title refers to Roberto Rossellini's 1945 film Rome, Open City, whose neo-realism brought urban life to the screen in a new, uncosmeticised way. The curators argue that this had repercussions on other media, with photographers of the city developing attitudes and aims that were distinct from those of 'humanist' pre-war practititioners, such as Andre Kertesz and Henri Cartier-Bresson.
To support this proposition, the 'international' selection of participants has a strong American bias: Robert Frank, William Klein and Garry Winogrand are here with oftreproduced images - raw, grainy, and disenchanted. British representation is sparse, so while the Smithsons' one-time collaborator, Nigel Henderson, appears (a Bethnal Green shopfront), there are none of Roger Mayne's shots of 1950s West Kensington and nothing from the magazine Picture Post, whose photographers were often out on the streets.
But as so many of the images here are arresting, omissions scarcely matter; and if they vary enormously in what they reveal of urban fabric, they do give food for thought.
Some of these photographs, you feel, could have been taken almost anywhere;
others are far more specific in their sense of place. It is examples of the former that visitors find in the first gallery: a wall with 54 prints by Beat Streuli, arranged in a grid.
These shots of self-absorbed passers-by, all taken in Oxford, are almost interchangeable with the much larger, individually framed prints of New York pedestrians that Streuli shows in the big upstairs room. The city is erased, while a look, a gesture, a moment of absent-mindedness is preserved.
Philip-Lorca DiCorcia also photographs passers-by but their urban context is more obtrusive: a New York avenue whose pavements are mirror-like after rain, a Tokyo of gleaming corporate chrome. DiCorcia's subjects are picked out by sensor-activated lights that they have inadvertently triggered, which gives these scenes the look of theatrical tableaux.
As this implies, there is a subtext to this exhibition: are we looking at a captured moment of 'reality', or at something staged? The aesthetic of post-war street photography was quickly appropriated for advertising and fashion magazines, as in Terence Donovan's series, Top Coats. One man-in-an-overcoat, posed in a patch of wasteland, could be the young Michael Caine in The Ipcress File. More recently, a Post-Modern knowingness, where everything is in quotation marks, has reinforced this tendency to stage things for the camera, as in Jeff Wall's elaborate light-box images included here.
It is with five of the photographers above all that we really scrutinise the built world.
Lee Friedlander surveys a street in Kansas City and intersections in New Jersey and New Mexico: these are inventories of signs, street furniture, telephone wires - the visual consequences of unconsidered design.
William Eggleston's small colour photographs in the American South offer seemingly random glimpses of places where 'urbanism' has never been on the agenda.
Last year's Turner Prize winner, Wolfgang Tillmans, is surprisingly impressive with six tall inkjet prints hung as a group, juxtaposing aerial overviews of cities with more intimate details - the abstract pattern ofroadworks seen from an upstairs window, human shadows on the pavement.
In an exhibition where the city, whether visible or not, seems to have largely negative connotations, two 1995 photographs by Thomas Struth - both taken in Wuhan, Japan, and rich in incident and information - suggest a more harmonious balance between a place and its inhabitants. People look at home in these busy but suitablyscaled streets, with their bicycles, market stalls and produce spilling on to the tarmac.
Earlier in his career, however, Struth's urban images were usually depopulated; there are some of Edinburgh in Open City.
The emptiness is not, as it can be, disquieting - there's nothing eerie - but it makes you look closely at the built fabric it exposes. The mask of human activity is removed - as it is in the two most haunting photographs in this show.
These black-and-white panoramas by Catherine Opie are both of St Louis, Missouri: a city seemingly in serious decline. A concrete-framed building stands alone in a void left by demolition; an empty parkinglot dominates its backdrop of redundant factories. They could be cliches of urban exhaustion and might well have been taken in other US locations, but Opie gives them a real power.
They certainly have no truck with glamour. But whether just dispassionate in intent, or more consciously dystopian, they are hardly an advertisement for urban design.