Microcosm: Portrait of a Central European City by Norman Davies and Roger Moorhouse. The standard one-volume history of Wrocław/Breslau, tracing the city through Bohemian, Habsburg, Prussian, German and Polish periods. Davies, a great popular historian of Central Europe, is the indispensable place to start.
Death in Breslau by Marek Krajewski. A Wrocław-set crime novel from 1933, the first in a series following the alcoholic, opera-loving police inspector Eberhard Mock. The atmosphere is heavy with the half-decadent, half-doomed mood of late Weimar German Breslau.
Flights by Olga Tokarczuk. The Nobel-winning Polish novelist has lived for many years in the Wrocław area. Flights, her best-known book in English, is a fragmented meditation on travel and the human body — not specifically about Wrocław but written by its most internationally celebrated resident.
House of Day, House of Night by Olga Tokarczuk. A more directly Lower-Silesian Tokarczuk novel, set in a village in the Sudety mountains south of Wrocław. Worth reading before any trip into the surrounding region.
The German War by Nicholas Stargardt. A history of how ordinary Germans experienced the Second World War, with several chapters devoted to the siege of "Festung Breslau" — the months-long Wehrmacht stand that destroyed much of the city in 1945.