On Monday night, Seventh and T streets NW will fill with the familiar bustle of concertgoers queueing up for a show. They’ll file through a glamorous marble lobby, perhaps pause at a long, illuminated bar and wait excitedly for the velvet curtains to part on a performance by breakout Washington rapper Wale. But it won’t be lost on anyone what they’re also here for: to see the Howard Theatre, once the nucleus of Washington’s Black Broadway, shine again.

It took only three decades.

Opened in 1910, the Howard was the first large music venue in the nation for black audiences, opening more than two decades before the Apollo in New York. Through the ’60s, it thrived, hosting the most important musicians on the circuit, including Billie Holiday, Miles Davis, Marvin Gaye and the Supremes.

But those were the good days, before riots in 1968 devastated the neighborhood, before urban flight, before the crime of the 1980s. The Howard Theatre was deemed a national landmark in 1974, but by then the calls to save the Howard — and the city itself — were reaching the level of a tea-kettle scream. By 1981, The Post had dubbed Seventh and T “D.C.’s meanest corner.”

Everyone wanted the Howard reopened, but “no one wanted to touch it,” recalls Chip Ellis, whose Ellis Development Group was tapped by the city in 2006 to restore the theater and, effectively, the neighborhood, with a major office and apartment project next door. “I said, ‘We’ve got to do this. One, we’ve got to bring back the history and make this a real destination, and two, if we lose it, we’re going to lose a part of our culture.’ ”

The audience on Monday will be treated to a sight that for a long time was unfathomable: The outside of the theater has been restored to look as it did in 1910 (a feat that required uncovering windows that were bricked over in a previous renovation). Inside is a venue that didn’t just receive a slap of paint, but fully embraced the zeitgeist.

The $29 million renovation has done away with the neoclassical architecture of the Howard’s heady early days and stripped the venue of its dingy, too-small theater seats. In their place are curvaceous black-walnut walls, dozens of cushy banquettes, 200-inch HD screens and VIP areas. The 12,000-square-foot venue will make room for more than 1,000 standing and — here’s what will set it apart from some other area music venues such as the new Fillmore — it will seat 600 at tables for more intimate supper-club-style concerts.

The Howard was also outfitted with a gleaming kitchen. Celebu-chef Marcus Samuelsson of Harlem’s Red Rooster (and a winner on “Top Chef Masters”) was brought in to create Southern-tinged dinner and brunch dishes (think: crab cakes in curry sauce, shrimp and grits, steak frites and herb-crusted salmon) and train the Howard’s staff.

The first several months are already booked with shows by Bad Brains, the Roots, Chuck Brown and Wanda Sykes, as well as Blue Oyster Cult and Michael Bolton. “We’re booking the space very eclectically,” explains Steven Bensusan, president of Blue Note Entertainment Group, which will operate the Howard. “One night we’re having a rock show, and another night we’re having an R&B or hip-hip show. We want to keep the room going.”

Keeping the Howard going — after many stops and starts that finally ended with its closure (and near foreclosure) in the 1980s — is everything. Particularly because this modern temple to live music, with Saturday-night concerts by Esperanza Spalding and Chaka Khan and Sunday-morning gospel brunches with the Harlem Gospel Choir, could well be the tipping force for a neighborhood on the brink of a vast transformation.

“We always said this was going to be the other anchor,” says Ellis, akin to 14th and U streets, an area that has experienced a dramatic revival in the past several years. But the question of when was crucial. “Nine years ago was not the right time,” Ellis concedes.

Neighborhood revivals are the story of the District over the past decade. New residents, restaurants and entertainment have replaced boarded-up storefronts in Logan Circle and on 14th Street NW and H Street NE at a rapid clip, due in part to a population boom of 20- and 30-somethings. The District drew a record 16,000 new residents between 2010 and 2011 alone.

Recently, they’ve begun moving to lower-cost neighborhoods that had been all but deserted after the riots, including LeDroit Park and Bloomingdale, which surround the theater. Following closely behind are a tentative few cafes and restaurants (see sidebar) that will soon creep up Seventh Street onto Georgia Avenue.

Ellis already had in the works the Progression Place office and apartment complex next door to the Howard, he says, “so we said we should go on and take this risk.”

Thirty vacant years, however, had left the Howard Theatre with a gaping hole in the roof, through which slipped both rain and various animalia.

“If you went in when it was raining, you had to keep your umbrella up, which was interesting,” recalls Michael Marshall of the firm Marshall Moya Design, who with Paola Moya was tasked with remaking the Howard’s interior.

“It was six months away from the roof falling in,” Ellis adds. “The water damage destroyed everything.” It also left room for a new vision.

Ellis brought on Blue Note Entertainment to run the Howard; the New York-based company also operates Blue Note jazz and B.B. King Blues clubs and the Highline Ballroom in New York.

The challenge was that the Howard is the first Blue Note venue that was once a theater; it was the first with a balcony, the first with a classical-style proscenium stage. “This being a historic theater,” Bensusan says, “we wanted to maintain elements of the theater but brought the interior a more modern club atmosphere.”

“Elegant” is how Marshall describes the Howard aesthetic. “Too much marble, too much glitz and glitter would be over the top,” he says. “So to get that sense of elegance, we tried to limit our palette.”

The few reminders of the grand legacy are poignant.

The lobby and several walls will glow with oversize, lighted black-and-white glamour shots of Holiday, Louis Armstrong, Duke Ellington and Lena Horne, all of whom played the theater in its glory days. And amid the velvety curves of the wall — meant to allude to the graceful swoops of grand pianos and guitars — and the roomy dining booths that line the edge of the theater sit five squat Corinthian columns, rather incongruous leftovers from the 1910 Howard that still prop up the second level all these years later.

Then there is the stage. Of all the elements that will matter to performers and audiences, it is the most notable. The original stage from the Howard remains intact, the one that had seen Cab Calloway scat and King wail. It’s the same stage that felt the click-clack of Ella Fitzgerald’s high heels when she had her career-making moment at the Howard, when segregated theaters had turned them all away.

One subtle but meaningful change: The designers lowered the stage a few inches, adding to the intimacy of the concertgoing experience.

“There’s going to be such a connection,” Marshall says. “Just as easily as you can see the stage, people on the stage can see the audience. That’s going to be great for the synergy and the energy of the audience, and it’s gotta be great for the artist.”