The obscure Gide requested by a friend was easily found at my possibly favourite Paris bookshop, an address of quiet competence near the Sorbonne. What, I wondered, would they have by Bernard Marrey, the architectural historian whose prolific output includes co-authorship of Architectures à Paris 1848-1914 and Paris-Banlieue 1919-1939, eccentric black-covered paperbacks which despatch me on irresistibly bizarre itineraries all over city and suburbs.

The assistant's computer listed L'abbé Pierre et Jean Prouvé and Matériaux de Paris, the former recent, the latter not, and neither currently stocked. But, advised the young lady, probably available at neighbouring X, multi-storeyed and brimming with new and remaindered books.

The notorious Librairie X! Scene of bibliophilic tussles with indifference, cussedness, and downright insolence, with inflexible regulation, discomfort, and, when crowded - as is frequently the case - a lingering wait to pay. My heart sank, and my left ankle throbbed in protest, thanks to that familiar hazard, for structural enthusiasts, of an earlier misstep off a low kerb while contemplating Haussmann-and-post façades along the rue Gay-Lussac, styled by students 'la rue du 10-11 mai' after a night of towering barricades and violently countered revolution during May '68.

Still, I had unearthed good, sometimes elusive titles at X, caught the occasional smile, and once, in the pervasive absence of chairs, sat reading, unmolested, for more than an hour on a step of the busy staircase. So, trying to walk evenly, I crossed the boulevard and was directed, by the haughty ...