Vertigo by WG Sebald.
For all the rich variety of novels out there, long, short, funny, sad, etc. etc., they generally adhere to a broad pattern: some characters get introduced, some stuff happens to them, some more stuff happens to them, in some cases just because it's exciting and funny, or sexy, or whatever, in other cases to reveal a few deeper truths about the human condition, yadda yadda yadda, the end.
For all the various and considerable merits of the books I've read and posted thoughts on here over the past year and a bit, most of them can be described in those terms because, well, that's what novels do. Very few authors are unmistakably and uncategorisably sui generis. WG Sebald is one.
You can tell this by looking at the categorisation of the book on the back cover: it's recommended you file this under FICTION/TRAVEL/HISTORY. So if even his publisher didn't know what to call it, what chance has the reader got?
On the face of it, this and the other Sebald I've read (The Rings Of Saturn) are ostensibly the story of some random wanderings by an un-named narrator (though the first-person style invites us to assume it's one WG Sebald, or a thinly fictionalised alter ego thereof) around Europe (Italy, Austria, Switzerland and eventually Germany in Vertigo, East Anglia in The Rings Of Saturn), with the various people and places encountered providing a jumping-off point for all manner of Proustian reveries about history and the author's past life and experiences. In the case of Vertigo these are split up by a couple of briefer interludes describing some incidents from the lives of Stendhal and Franz Kafka respectively. Even here Sebald refuses to make any concessions to the reader; the chapter on Stendhal never refers to the author by his famous nom de plume; you have to do the legwork to establish that that's who Marie-Henri Beyle was better known as.
The text is broken up by various black and white images, some obviously related to the text near which they appear, some not. Some of these are Sebald's own photographs, others are old postcards, restaurant receipts, handwritten notes and so forth. All of which, combined with Sebald's own hilariously glum and lugubrious tone when relating his own wanderings (often deeply mundane when you strip away the flights of fancy they provoke; at one stage he spends three days in his hotel room in Venice living on red wine and sandwiches) lends the whole thing a strangely mournful tone.
It's hard to characterise why these books are as weirdly affecting as they are; in the case of Vertigo it's probably as much for what he doesn't include - he returns to the village where he was born in 1944 and relates various stories in which his parents feature, but without mentioning anything about the war - this odd omission of something which must have had a profound effect on his childhood merely throws it into sharper relief.
Sebald spent most of his adult life in England, where he was a lecturer at the University of East Anglia until his untimely death in a car crash in 2001. It would have probably given him a perverse satisfaction to note the strangely Sebaldian juxtaposition of a New York Times interview to promote his last novel Austerlitz, and the recycling of large chunks of that interview in his obituary a mere four days later.