Düsseldorf produces more Altbier than any other city in Germany, a distinction held since the 19th century when coal-fired copper kettles lined the cobbled lanes of the Altstadt and brewmasters refused the pale lager revolution sweeping Bavaria. The term "Alt" translates to "old," a declaration of allegiance to top-fermented brewing methods that predate refrigeration. Five historic brewhouses still stand within a half-kilometre radius of Bolkerstrasse, each pouring dark amber Altbier from wooden casks tapped twice daily. The beer is served in cylindrical 200-millilitre glasses called Stangen, slim enough to stay cold through rapid consumption, and replaced by blue-aproned Köbes waiters who mark chalk tallies on coasters until a patron signals surrender by placing a mat over the glass. Altbier ferments warm and conditions cold, a hybrid technique that yields a copper-colored brew with caramel malt body and pronounced hop bitterness. The style nearly vanished in the postwar decades when industrial Pilsner claimed national dominance, but Düsseldorf's breweries held firm, operating both as taverns and breweries under the same roof. Zum Uerige, founded in 1862, still brews in open copper vessels visible through cellar grates on Berger Strasse. Füchschen, established in 1848, maintains oak barrels in its timber-beamed hall. Schumacher, the oldest Alt brewery in continuous operation since 1838, supplies its beer exclusively to its own tavern on Oststrasse. These are not museum replicas but working production breweries, each fermenting 2,000 to 5,000 hectolitres annually in the same buildings where their recipes were written. The Altstadt's nickname, "the longest bar in the world," reflects a density of 260 licensed establishments compressed into less than half a square kilometre, with brewhouses anchoring a lattice of bakeries, mustard shops, and schnapps distilleries. Visitors move between brew halls in a ritual called a "Zug," a progression structured around beer rather than food. Guided beer walks navigate this quarter in two-to-three-hour circuits, stopping at four to five breweries and including behind-the-scenes access to copper brewing floors and cold cellars where Alt is lagered. These tours explain the technical distinctions between house recipes—Uerige's pronounced hop bite versus Füchschen's softer caramel finish—and decode the unwritten rules governing service speed, glass replacement, and the chalk-mark system. The experience remains rooted in function: chairs are communal, menus short, and the beer unchanged since the first casks were tapped beneath gas lamps along the Rhine.