Reviewed - My Architect: A Son's Journey: Louis Kahn, the Estonian-born architect whose monumental romanticism gave soul to some of the great American buildings of the last century, died in the men's room of New York's Penn Station in 1974, writes Donald Clarke

He had been travelling home from Dhaka and in his pocket was a passport with his home address crossed off. It took two days to locate his family.

A quarter of a century later his son, the documentarist Nathaniel Kahn, devoted five years of his life to making sense of a father he never quite knew. The result is, inevitably, an incomplete portrait of a complex person, but in between introducing us to some extraordinary buildings, Kahn's film reveals some arresting truths about the damage otherwise decent men can do to those they love when their thoughts are elsewhere.

Louis Kahn's social arrangements were far from conventional. His obituary listed his only immediate family as his wife Esther and their daughter Sue Ann. He had, however, another daughter by a younger colleague, Anne Tyng, and a son, Nathaniel, by Harriet Pattison, a landscape architect. Every week Louis had visited Nathaniel and then slipped back to Esther.

As Nathaniel moves among the surviving family members - of the major players only Esther is no longer with us - he encounters shock, anger and dismay, but virtually everybody he talks to seems to retain affection for his father. Then again, people do tend to speak well of the dead. Despite the range of stories that Nathaniel hears, one gets the impression that he feels closest to his father when in the presence of his architecture. There is certainly something a tad dubious about such an approach - plenty of monsters have produced gorgeous art, after all - but it would be churlish not to permit the director his moments of communion. In one rather lovely sequence he roller-blades around the open space at the heart of the overpowering Salk Institute in La Jolla, California - a little boy proudly showing off his skills before his dad.

Kahn moulds My Architect into a seamless blend of personal journey and architectural masterclass and, though we could have done without the voice-over's occasional dips into bathos, the picture radiates warmth and good intentions.