Josef Groll's 1842 recipe for Pilsner Urquell created the world's first golden lager, a beer so revolutionary that within two decades every brewery in Central Europe was attempting to replicate its clarity and hop-forward bite. The Plzeň brewery sits on a network of nine kilometers of sandstone cellars dug in the thirteenth century, chambers that hold a constant 6°C and sheltered barrels of aging beer through wars, occupations, and the rise of industrial brewing. Today those cellars remain the final maturation stage for Pilsner Urquell, the only major lager still conditioned in oak rather than stainless steel. A pilsen brewery tour from prague brings visitors ninety kilometers southwest to U Prazdroje, the red-brick brewery complex that has anchored Plzeň's industrial quarter since 1839. The hour-long tour descends into the original cellars, where unfiltered beer is drawn directly from wooden casks under vaulted stone arches lit by gas lamps. Above ground, the brew house retains its 1890s copper kettles, polished to a mirror finish and still in daily use. The decoction mashing process unique to Pilsner Urquell takes five hours, triple the time of modern fast-brew methods, and visitors watch brewers rake spent grain from the mash tuns by hand. The interactive museum opened in 2021 traces the Burghers' Brewery's evolution from a municipal venture—founded when Plzeň's citizens grew tired of poor-quality beer—into a global brand. Exhibits detail the 1295 brewing rights granted by King Wenceslas II, the introduction of Saaz hops from Žatec, and the role of Bavarian brewer Josef Groll, whose contract lasted just three years but whose recipe remains unchanged. Visitors sample three styles: the flagship Premium, the unfiltered cellar pour, and a limited-release dark lager brewed to an 1890s recipe. The tasting room overlooks the brewery's private rail siding, where tanker cars still depart daily for export markets across Europe and North America.