Architecture: Up the stairs to a world of dreams: A new television series shows how film-makers and artists have harnessed the imaginative power of buildings. Rowan Moore reports

IF YOU ask architects to explain their work, they will tell you about site, brief and client, about light and views and fresh air and other such reasonable things. They might talk of construction and materials, about composition and even of style. They will, however, say nothing about what their buildings might mean to those who inhabit them.

Yet buildings are fertile with imagery, intended or unintended by their designers. The house of our childhood shapes our imagination far more than the world outdoors; windows and stairs in that house have an emotional potency when we are very young that is far greater than the sum of their function and decoration. It is not architects, but writers, painters, and above all, film makers, who exploit this power: think of what Edgar Allan Poe can do with a wall, Vermeer with a window or Hitchcock with doors and stairs.

Think of the Odessa steps in The Battleship Potemkin, the window in Rear Window or the echoing interiors of Xanadu in Citizen Kane. Then think how dull are the doors and windows in some of our most admired buildings; mere sheets of glass and panels of wood that barely nudge our senses.

Starting on Friday, BBC2's new series, Architecture of the Imagination examines the imaginative power of doors, stairs, windows, bridges and towers. Directed by Mark Kidel for Third Eye Productions, each programme is an inventive mixture of film clips, paintings and rather odd interviews - for example with Sir Peter Holmes, the recently retired chairman of Shell who walks up 52 flights of stairs to his office each day. Each programme is followed by a pertinent film - all made in the Forties - such as Waterloo Bridge, starring Vivien Leigh, or Fritz Lang's Secret Beyond the Door.

This ambitious series has its faults. There is too much of James Hillman, a pop psychologist who advises architects and town planners, stating the obvious. And - seemingly overwhelmed with exciting visual material - the programmes can seem overburdened and structureless. Yet the series addresses certain fundamental aspects of architecture and buildings that are rarely probed.

Seen through the media of paintings and films, buildings literally come to life. In a Fra Angelico Annunciation hung in the Prado, Madrid, for example, the drab architecture of the Virgin's house becomes iridescent with new life at the moment of divine conception: columns sprout leafy capitals, while the vault of her loggia becomes a starry sky.

In the Hollywood shocker Die Hard, Bruce Willis's co-star is a Los Angeles skyscraper that suffers damage at about the rate at which Willis is himself battered. As his feet are lacerated, its lobby is blown out; its top is demolished as his head is punched. When Willis's skin is torn, the glossy cladding of the building is ripped apart. The skyscraper's guts - its service shafts, ducts and air- conditioning system - are synonymous with human organs.

In some films, buildings represent both body and mind; in Psycho, for example, the house above the murderous motel is the warped mind of Norman Bates, as well as the ruined body of his mother.

Architecture of the Imagination makes particularly good use of scenes from David Lean's Great Expectations in which Pip, embodying outdoor wholesomeness, stands at the literal and metaphorical threshold of the devious interior world of Estella and Miss Havisham. By entering their dark house, he will change his life.

In Antonello's painting of St Jerome in the National Gallery, the meticulous architecture of the saint's study reflects the orderliness of his divinely inspired mind. It had previously been usual to depict the saint in a hermit's cave.

In The Magic Mountain, Thomas Mann makes the inner workings and design of a Swiss sanatorium reflect both the mind of his listless anti- hero and a disarranged continent on the brink of war.

In David Lean's Brief Encounter, Celia Johnson gazes on to a train window, reflecting both her inner turmoil and the dream world that she wants but refuses to allow herself with a man she loves more than her husband.

Neither Mann nor Vermeer, Lean nor Antonello had to worry about such mundane matters as keeping windows watertight or walls sound, yet Architecture of the Imagination serves as a reminder that architects too often shy away from the world of dreams and allegory as they attempt to create a rational and functional world.

If film, literature and painting can draw so profitably from the inner world of stairs, corridors and windows, so too can architecture and those who shape the literal world of buildings.

Architecture of the Imagination, 9.30pm, BBC2, Friday 30 July for six weeks.

(Photograph omitted)