Last weekend, O'Sullivan's Irish Pub went from being a cozy spot for darts and a pint of Guinness to being one of Clarendon's biggest bars. An expansion into two neighboring storefronts – an aromatherapy store and a deli – created a "Whiskey Bar" room, with a large bar showcasing nearly 100 whiskeys, and a new dining room. More importantly, capacity almost tripled, and now stands at 297. "We took over the lease for [the other businesses] last year, and we talked about what we could do with space," says manager David Morrin. "We realized that, if we had 30 whiskeys, and they were all selling well, why not go all out and make it a dedicated whiskey bar?"

The new entrance to O'Sullivan's Irish Pub, which is located on Wilson Boulevard, leads directly into the Whiskey Bar. (Fritz Hahn/The Post)

The whiskey collection is international in scope: There are 25 from Ireland, 25 bourbons and 30 Scotches, with the rest a mix of American, Japanese and Canadian whiskeys. Plans are in place for "at least 15 flights," which Morrin says will be educational in nature. He envisions a guest being able to try three different ages of Glenlivet Scotch (the bar currently has five), or comparing a 12-year-old bourbon, a 12-year-old Scotch and a 12-year-old Irish whiskey. The future also holds monthly whiskey tastings – Glenlivet has already held one – and a whiskey club, with prizes for trying a certain number of bottles or styles.

That said, I doubt it will attract a snobby drawing room that wants to debate the merits of single malts from Campbeltown. The new bar, with its red walls and stained wood, still feels like O'Sullivan's. Dozens of bottles of whiskey may be lined up in front of a huge Guinness-logo mirror, but soccer plays on the TVs and rock music blasts from the speakers. There's much more space to spread out at the long bar counter, and at tables in the back. One thing you'll notice: An expanded number of draft beers, with a couple of microbrews from Founders and New Holland joining the trinity of Guinness, Harp and Smithwick's.

Many things will remain the same, though: Bands still perform on a stage in the "original" O'Sullivan's on Friday and Saturday nights, the pub quiz is on Wednesdays, and karaoke is featured on Tuesdays. (Morrin does helpfully point out that the new whiskey bar and the old bar have separate sound systems, so people hanging out at the new bar don't have to listen to karaoke singers.)

If you liked O'Sullivan's convivial vibe before, you'll enjoy the new space. If you like whiskey or whisky, you'll like the new space. And if you are tired of overcrowded Clarendon bars, you'll enjoy the extra elbow room.

The new Whiskey Bar at O'Sullivan's looks different than the original pub, but it's still simple and traditional. (Fritz Hahn/The Post)