Cologne has a saying: kölsch is the only culture you can drink. After one writer spent ten hours working through seven of the city's traditional brewhouses, the verdict is in — and the winner is a bar that refuses to sell its beer anywhere else.

First, the rules. Kölsch has held EU protected geographical status since 1997, meaning anything labelled as such must be brewed within 50km of Cologne to the terms of the 1986 Kölsch-Konvention: a light, clear, hop-forward, top-fermented full beer. Think champagne's rules with a pale ale's drinkability. The ritual matters too. A deadpan, blue-aproned waiter — the köbes — keeps replacing your 200ml stange glass from a circular kranz tray, pencilling tallies on your beer mat, until you cover your glass with it to stop the flow.

The standout was Brauhaus Päffgen on Friesenstraße in the Friesenviertel, pouring since 1883 and scoring 9.5/10. It's one of the last brew pubs that won't bottle for shops — you drink there or take home a wooden keg. The kölsch is tapped from wooden barrels, with grassy hops, stone fruit and a crisp bitter finish. Look for the old wooden beichtstuhl, the elevated 'confessional' booth where the innkeeper once kept an eye on the floor. As one waiter put it, kölsch isn't a drink but a religion, and Päffgen is the church.

Close behind, on 8.5, was Brauerei zur Malzmühle by Heumarkt, the city's second-oldest brewery (1858), rebuilt after wartime destruction behind its surviving stone portal. Its maltier, honey-tinged Mühlen Kölsch got Bill Clinton's seal of approval in 1999 — 'Ich bin ein Kölsch' — and the room mixes hi-vis workers with suited executives. Brauhaus Sünner im Walfisch (8/10), in a 17th-century step-gabled house reassembled brick by brick, serves the city's oldest brewery's peppery, dangerously quaffable beer in medieval-style timber rooms.

The cathedral-facing halls fared worse. Früh am Dom (4.5) is internationally famous but tour-group-clogged, with a beer that lacks crispness. Sion (6), slick and renovated since its 1912 founding, is better for dinner than a session. Gaffel am Dom (6.5) pours a reliably hoppy brew — the same one sold at Cologne Bonn airport — but redeems itself with a superb himmel un ääd (black pudding, mash and stewed apples). Peters Brauhaus scored 7 for its stained-glass beauty and balanced beer, if you catch it busy.

Prices barely vary: €2.50-€2.60 a glass everywhere, so a crawl costs less than a round of cocktails back home. Skip the souvenir glasses near the cathedral and head to Friesenviertel for the real thing.