In 1967, the violinist Francis Fortier was 27 years old and $10,000 in debt. The New York musician had just finished staging the second annual Bar Harbor Music Festival, a summer concert series he had founded. The month-long festival features classical pianists, opera singers, and other fine musicians from around the world. But Fortier had been too generous paying the artists and housing them at pricey island rates that year, and he had to answer to the Bar Harbor Chamber of Commerce, which helped fund the festival.

“I faced the music,” he said. “I looked those businessmen in the eye and I said that everyone would be paid back within the year.”

Luckily for Fortier, there were plenty of merchants and philanthropists — like former Vice President Nelson Rockefeller and Peggy Colgate Eagan (of the Colgate-Palmolive fortune) — in New York and Bar Harbor, who saw the promise in his vision for the festival, and they helped underwrite his debts. Nearly half a century later, the festival is a musical proving ground for world-class, emerging artists.

“The new composers and younger performers will someday be at The Metropolitan Opera,” said Bronwyn Kortge, director of Mount Desert Island High School’s vocal program and the Blue Hill-based Bagaduce Chorale. “That’s exciting to know you’re catching them at a wonderfully intimate place.”

East Coast-based Ardelia Trio will perform at 8 p.m. on Friday, July 22, at the Bar Harbor Congregational Church. The chamber group, which includes violinist Janey Choi, Clara Yang and Jihea Hong-Park, will play music by Beethoven, Josef Suk and Shostakovich.

This year’s festival, which runs Sunday, July 3, through Sunday, July 31, will be filled with intimate places. The opening concert will be held in the Maine Sea Coast Mission’s historic brick mansion, overlooking Frenchman Bay. There, Carnegie Hall veteran Keith Harris will sing Schumann in his warm baritone, accompanied by the internationally known pianist Cara Chowning. During intermission, high tea will be served “on real china, not Styrofoam!” Fortier said.

The opening concert mansion is one of eight iconic Bar Harbor locations that Fortier hand-picked for his concert series. Each venue has a unique trait, like the powerful acoustics of the white clapboard Bar Harbor Congregational Church, or the granite fireplace at The Jackson Laboratory, a nonprofit facility that has made groundbreaking gains in cancer and diabetes research.

“Chamber music came from string concerts in English mansions,” Fortier said. “Not a coliseum with 5,000 people.”

The venues might be intimate, but the concerts held in them are expected to draw record numbers since the Bar Harbor Festival’s 50th anniversary coincides with the 100th anniversary of Acadia National Park. Fortier said this year’s online ticket sales have already broken last year’s record and, in honor of the park, two composers wrote Acadia-inspired pieces for the festival.

One of the composers, Eric Ewazen — who is composer-in-residence at New York’s The Juilliard School — fell in love with Acadia during his visit in 2013. His piece written for brass, “Scenes from the Great Park,” includes movements named after the sun rising on Cadillac Mountain, and the ocean waves crashing on Thunder Hole. “Scenes” will make its world premiere Wednesday, July 6 — the festival’s opening night — and be performed by the Massachusetts-based quintet Brass Ventures at the Bar Harbor Congregational Church.

“I just thought of the challenge of getting it open,” the 77-year-old recalled. “I could never have imagined it would become this big.”

Fortier himself will pick up the baton Wednesday, July 27, at the Blackwoods Campground Amphitheatre at Otter Creek, where he will lead the Bar Harbor Festival String Orchestra through Edmund Cionek’s Acadia-inspired piece “Songs of the Sky.”

“The performers can’t wait to play there,” said Fortier, “because the audience is so appreciative; even the dogs sit there, quietly listening. And when everyone claps, the dogs bark!”

For Fortier, that moment —like the 49 others that came before it — will make all his hard work worth it.