You may have seen the posters on the T: not-too-bright red and modest off-white, titled “Boston Calling,” with a list of bands in unassuming block letters. Fun. The National. Maybe you did a double-take, as I did, and looked further down: The Shins. Dirty Projectors. Andrew Bird.

Maybe, like me, you were surprised to see such a hip lineup at a heretofore nonexistent festival in Boston. Maybe you weren’t. But I should warn you now: Boston Calling Music Festival, which will take place on Memorial Day Weekend in City Hall Plaza, has already sold out, but for a handful of VIP tickets.

It’s still worth talking about, perhaps for the very reason co-founders Brian Appel and Mike Snow decided to throw the event in the first place.

“It felt like there was not one ... defining Boston festival,” says Appel. “So we’re not getting ahead of ourselves and saying that’s what we are, but that’s what we hope to be. We’d like to be the music festival that people think of when they think of Boston, in the same way Austin City Limits or Lollapalooza or any of those festivals have their association with their respective cities.”

Appel had been planning a large outdoor urban festival as director of marketing at Phoenix Media/Communications Group when The Boston Phoenix and WFNX radio went under. So he and Snow, previously operations director for WFNX and then Radio BDC, founded Crash Line Productions and resurrected the project on their own.

Their big break came when an investor put them in touch with Aaron Dessner, guitarist for Brooklyn-based (and Cincinnati-originating) band The National (pictured at top). According to Appel, the band was eager to help out because they loved playing in Boston—simple as that.

“They’re genuinely great guys,” says Appel, “and I think they took a lot of enjoyment out of seeing this from its infancy stage—which I suppose we’re still in—and then come to fruition."

In the end, Dessner agreed to curate the festival and The National signed on to headline. With the help of booking agency Bowery Presents, they ended up with a lineup of pop-oriented indie-rock with just enough niche appeal to give it a bit of an edge. Sure, Fun. is all over the Top 40 stations and Marina and the Diamonds (the stage name of Marina Diamantis) is cut from Katy Perry’s mold; but Andrew Bird has a sort of cerebral, eccentric sensibility and the Dirty Projectors are defiantly experimental. Then there is the ominous cacophony of MS MR, the spacey dissonance of Youth Lagoon, the synth-infused urgency of St. Lucia.

The festival will feature a total of 18 acts, two main stages, a beer garden, and a plethora of food trucks and vendors. Most importantly, says Appel, ticket holders will be allowed to come and go as they please throughout the weekend.

Appel and Snow’s only other requirement was that the bands be family friendly, at least this year. Kids 10 and under get in free. “We curated a lineup that we thought would be manageable for the cops to deal with, manageable for the space that we have,” says Appel.

Appel hopes to see the lineup diversify and grow, although he says it will never reach the scale of Coachella or Lollapalooza, simply because the city is too small.

One thing Appel intends to emphasize at future festivals is the local music scene. This year’s bill includes two homegrown bands: post-R&B outfit Bad Rabbits and instrumental rockers Caspian.

“We wanted to make sure local Boston bands were represented, and we do have a local band on each day of the bill. As we move forward as a company—hopefully this is not the last thing that we ever do—we’ll have an expanded focus on the local music community,” Appel explains.

“We—my company and the people who work here—are from this area, and we’ve lived here forever. And we know the bars, and we know the clubs, and we know the bands. So we want to make sure everybody is benefitting when we’re able to bring more people into the city for events like this.”

Amelia Mason is a writer and musician living in Cambridge. Those pesky “day jobs” she has to “make money” really aren’t worth mentioning. Naturally, she also has a blog: blog.ameliamason.com.