It’s no secret that Portland, Ore., is the center of the craft beer universe. In the late 1980s, when most drinkers were still chugging light beers and lapping up the antics of Spuds MacKenzie, Portland brewmeisters were turning out flavorful artisan suds modeled after European exemplars. Fast-forward a quarter-century, and craft beer culture has gone global. Fizzy yellow beers are positively passe, and even casual drinkers these days know their IPAs from their hefs and pilsners.

Yet Portland remains in a league of its own, pushing craft brewing to new, hoppy and occasionally weird heights. For tippling travelers and beer snobs, it’s a liquid Shangri-La.

And the vanguard of Portland’s craft brewing scene may well be the Central Eastside. Well off the tourist map, the gritty ‘hood sits across the Willamette River from downtown Portland. Here, railroad tracks and buzzing interstates give way to a post-industrial panorama: block after block of aging factories, brick warehouses and auto-repair shops. Yet in recent years, vintage boutiques, cafes and brew pubs have begun popping up, the advance guard of a wave of urban renewal. For thirsty locals (and intrepid travelers), the Central Eastside is fast becoming the place to sample cutting-edge brews.

My first stop is the Cascade Brewing Barrel House, on busy Belmont Street in the industrial heart of the Eastside. On a sunny afternoon, dozens of bicycles are locked to the patio railing — a clear vote of approval from Portland’s bike-riding, beer-swilling hipsters. I make my way through the beer garden out front and into the barrel house, where no fewer than 23 house beers are on tap, from hoppy IPAs to farmhouse-style saisons and straw-colored pilsners.

But I’ve come for something really special: the sours. Sour beers may well represent the final frontier of craft brewing. Popularized in Belgium, these beers are traditionally brewed with live lactobacillus cultures, the same bacteria used in yogurt. This imparts a tangy, tart taste, unlike that for any other beer out there. Sours are also notoriously difficult to get right, taking months to ferment and sometimes years to mature.

Cascade has the process down to a science. I pull up a stool to an oversize barrel doubling as a table to sample the menacingly named Cherry Bourbonic Plague. The brewmeisters at Cascade start with a recycled bourbon barrel, aging the beer in it for six months. Then they throw in some sour pie cherries for good measure and leave it for another two years.

The result? Well, there’s a reason it’s called a sour. But once you move beyond the tart attack, it’s all dark cherries, dates and oak dancing on the palate, with a bourbon-flavored finish. Initiated, I dive deeper into sour country, sampling wheat beer styles and exotic variants with honey, ginger and lime. Be forewarned: Because they’re aged, sours pack a punch. But the handy to-go growlers and grenades at Cascade make it easy to grab one more for the road.

Properly puckered, I plunge back into the Eastside afternoon, skirting a vacant lot grown tall with weeds, then hanging a sharp right to reach Green Dragon, another craft beer mecca. A rambling complex embracing a beer garden hung with paper lanterns, a rustic warehouse-cum-bar and a brewery, Green Dragon takes up nearly half a city block. At happy hour, it’s packed and boisterous, bearded drinkers jammed elbow to elbow at picnic tables, downing pints and scarfing discounted bratwursts, sliders and other pub fare. Mounted above the bar, a cow head in a Mexican wrestling mask presides over the chaos.