About an hour after my flight touched down at O’Hare, and five blocks after I hopped off the El’s Blue Line stop at Logan Square, Chicago embraced me with a warm hug in the form of a barrel-aged doppelbock — a mini goblet of sweet vanilla lusciousness with a boozy note of rum.

It was just a beer, yes, but no ordinary lager; more of an evolution into a higher form. White oak barrels that once held Kentucky bourbon, then Jamaican rum, had their third alcoholic incarnation here in aging this doppelbock for seven months. The result is a beer more complex than most, as additional flavors bleed from inside the staves — deeper woody notes that play to a beer’s bass and an extended taste that finishes with a nip of hard liquor.

Chicago is a bastion of these bourbon-barrel-aged craft beers. That’s why I was in town last fall, during the weekend of the Festival of Wood and Barrel-Aged Beer. The Oscars of this esoteric beer sect, FoBAB, as it’s called, draws more than 80 brewers from across the continent in a contest to name the best.

FoBAB general admission tickets sold out online in five minutes last August, and I missed out. But no matter, there are so many breweries in Chicago barrel aging their beers, many within an easy walk from a light rail stop, that I plotted an El tour near downtown and the North Side. I was hoping FoBAB would put the entire city into a barrel-aged buzz. It was a bet that paid off — I found and sipped 25 beers over three days.