The flickering, monochrome film shows an elderly gentleman with a snow-white beard chatting to a friend in an enormous, sunlit garden. Beside them, towering hollyhocks wilt in the heat and bulbous peonies nod dopily, as if in agreement with what they are saying. But a commentary informs us that the footage was obtained in secret: the subject had a hatred of being photographed and was notorious for ruining any attempts to do so by "making faces". A fascinating idiosyncrasy, given that Sigmund Freud, born 150 years ago this year, spent most of his life scrutinising others.

His insights into the unconscious are explored in an enigmatic new exhibition, "The Interpretation of Dreams", which runs alongside the film at the Freud Museum. Its location, 20 Maresfield Gardens, in Hampstead, north-west London, was also the house in which Freud died. Although he lived in Vienna for more than 80 years, he was forced to flee the city when the rise of Nazism made life intolerable for its Jewish citizens. In the documentary, which is narrated by Freud's youngest child, Anna, the images of halcyon summer afternoons give way to those documenting Freud's escape and subsequent arrival in London, accompanied by his extended family and beloved chow-chow Jofi. By this point, Freud was an invalid, wreathed in blankets and racked with pain from the cancer of the jaw that would kill him less than a year later, on 23 September 1939.

Anna became a pioneer in the field of child psychoanalysis, living on at Maresfield Gardens until her death in 1982. Yet the house retains the feeling of being a temporary refuge, a stopping-off point for a family in transit. This poignant atmosphere is largely a result of a discrepancy between the house and its furniture, almost all of which was shipped over from Freud's apartment in Vienna. The heavy, burnished Austro-Hungarian empire tables, chairs, chests and wardrobes (delicately painted with alpine flowers, vistas of holiday spa towns and inscriptions in German, lacquered over to preserve against decay) sit uneasily within the walls of a light and airy English villa.

For Freud, dreams were "a royal road to a knowledge of the unconscious". Threading their way through the rooms of Maresfield Gardens, a delicate progression of displays introduces some of the more notable dream symbols from his casebooks. Night-time reveries relating to sexuality, ambition, birth, death, yearning, disappointment, motherhood and fatherhood are variously reflected by broken candles, children's toys, a staircase, a lamp, a loom, botanical sketches, an oil painting of a dark river, a bowl of cherries, a box of matches, potted violets and a half-open cupboard.

Freud regularly used symbolic objects as reference points during psychoanalysis. His consulting room, which has been preserved as it stood on the day of his death, is crammed with a significant collection of antiquities from ancient Greece, Rome, Egypt and the Orient. Every surface groans with busts, heads, vases, pots, jars, stones, fragments of hieroglyphs and pieces of pottery. Freud confessed his passion for collecting was second in intensity only to his addiction to tobacco; appropriately, a half-smoked cigar lies in an ashtray on his desk, alongside a beard comb and a pair of spectacles.

However, even these personal relics are upstaged by the piece of furniture that nestles against the wall, covered in a rich Turkish throw and tapestry cushions: Freud's consulting couch.

On this simple divan, patients were asked to "free associate", without consciously sifting or selecting, as Freud sat beside them, out of sight in a green baize tub chair. Michael Molnar, director of the Freud Museum, testifies to the room's impact: "Many have cried here. In fact the word 'emotional', in various languages, is one of the commonest terms used in the visitors' book - and people often try to jump the rope cordon and lie on the consulting couch, setting off an automatic alarm in the process." One can understand the compulsion: the couch's exotic drapery enhances the notion of it being a kind of magic carpet, a levitating transport to a world of absolute understanding.

When I'm granted the privilege of sitting on it, I am embarrassed to find that as I jolt down and sink into flaccid upholstery (the springs and horsehair having long since lost their buoyancy), my mind is monopolised by something altogether less fanciful - the seemingly absurd word "lozenge".

It's not until the following morning that I make the connection. From my dreams, I retrieve the buried memory of my first sighting of a childhood neighbour in Wales: an elderly Jewish refugee from Germany, pulling up weeds in his garden, as I sit atop a pile of saggy old tyres in mine, eating cough sweets.

"The Interpretation of Dreams" is a semi-permanent installation at the Freud Museum, London NW3. For further information call 020 7435 2002 or see www.freud.org.uk