Arriving in Trieste in 1909, the Viennese playwright Hermann Bahr felt as if he were “nowhere at all”, adrift in a city of ghosts. Anyone visiting Trieste for the first time today may experience a similar sense of dislocation, because there is something mysterious and unaccountable about the cosmopolitan Adriatic port, something to do with its lost past as the great seaport of the Habsburg empire and its moribund present as a buffer-zone between Italy, to which it now reluctantly belongs, and the Balkans.

James Joyce, who lived in the city for more than a decade, had his own name for Trieste - “Europiccola”, a little Europe - and the city through which he moved as an impoverished teacher of languages certainly mirrored the polyglot diversity and ethnic confusion of the old Austro-Hungarian empire. Today, Trieste is quieter, but it remains a place where you begin to understand the conflicts in the Balkans, and how south-east Europe seems forever doomed to be split along the ancient fault-line separating Roman Catholic from Orthodox, East from West.

Trieste is one of those mercantile city-ports - such as Odessa or Danzig/Gdansk - that ought to belong to no country; indeed there was an attempt after the Second World War to create the “Free Territory of Trieste”, a strategic non-aligned zone between rival ideological blocks. Before Trieste was ceded permanently to Italy in 1954, what was known as Zone B of the Free Territory, incorporating the Istrian peninsular, was assigned to Yugoslavia. There are elderly Triestines I know who have never ceased mourning the lost “Italian” towns of Koper, Piran, Umag and Novigrad, which are now divided between Slovenia and Croatia.

Jan (then James) Morris first arrived in Trieste as a young soldier at the end of the Second World War and has remained haunted by the “crepuscular” city ever since. For Morris, Trieste is an “allegory of limbo, in the secular sense of an indefinable hiatus”. As she walks the streets of what the locals still call their “little Vienna” because of its splendid baroque and neo-classical architecture, she is accompanied by phantoms, and her Trieste becomes, though this is never said, what Mikhail Bakhtin calls a “chronotope”, a place which allows us to range through time and space, to see the past in the present.

But to live with too great a sense of the past and of time passing can lead to a dangerous nostalgia, and Morris, though alert to such dangers, nevertheless allows herself to be seduced into concentrated melancholic rapture, with every street and cafe holding wistful memories of loss. One senses that she sees in the ambivalence of Trieste - its shifting allegiances and ethnic muddles - something of her own inner ambivalence: that of a woman who was once a man, and of a writer who concedes that her books are no more than “smudges of graffiti on the wall”.

Morris - like Joseph Roth and Stefan Zweig before her - is moved by the grandeur and historic failure of the multiethnic Habsburg em pire, and this book can be read as a lament for the world of security that was shattered by the murder of Archduke Franz Ferdinand and his wife, Sophie, on June 28, 1914 (their coffins passed through the streets of Trieste before being sent by train to Vienna). Many others have passed through Trieste, too - Rilke, Freud, Stendhal, Egon Schiele, Casanova. Perhaps they were attracted there by a sense that they had reached the end of something, if not the “last breath of civilisation”, as Chateaubriand put it in 1806, then the last town in Western Europe, which remains suspended on an ancient precipice between Rome and Byzantium, water-surrounded and borne back ceaselessly into the past.

Jan Morris has also reached the end of something, in her case the end of the writing life. If, as she says, this is to be her last book, then she has left us with not only an unconventional travelogue of fascinating complexity, but also one of the most impressive and subtle meditations on old age that I have read, much more than mere smudges of graffiti on a wall. The rest is silence.