For nearly half a century, the old north entrance of the Philadelphia Museum of Art, the entry mostly notable for the trucks parked in front of it or backing into it, has been off-limits to anyone not seeking to load at its dock facing Kelly Drive.

But Wednesday, 28 second graders from Bache-Martin Elementary School walked through a torrential downpour of red streamers, past the new glass entrance, past the great old studded wooden doors, and into what William R. Hite Jr., superintendent of schools, called their future.

Closed to the public since 1975, the dramatic entrance leads to a tiled vaulted walkway more than 600 feet long with a 24-foot-high ceiling, running across the length of the museum. All has been refurbished, redesigned, and rethought.

Leslie Anne Miller, left, PMA board chair, raises her arms while streamers fall on architect Frank Gehry next to William Hite, right, school district superintendent. The museum's old north entrance has now reopened.
HEATHER KHALIFA / Staff Photographer
Leslie Anne Miller, left, PMA board chair, raises her arms while streamers fall on architect Frank Gehry next to William Hite, right, school district superintendent. The museum's old north entrance has now reopened.

As the museum moves forward with its “core project" — the opening up of its interior spaces and creation of thousands of square feet of new gallery space — the vaulted walkway becomes a key thruway for getting visitors where they want to go.

Hite was there Wednesday to commemorate the reopening, along with Mayor Jim Kenney, museum leaders, and architect Frank Gehry, mastermind of the whole plan.

“This entire museum is Philadelphia’s classroom,” Hite said, moments before the second graders entered. "What has been accomplished today is a gift to our schools, and our children’s future.”

The new entrance has school-bus drop-off spaces and the entrance leads to new educational areas, including a classroom studio designed for schoolchildren.

(There’s also a new museum store and an espresso bar for parents and other grownups.)

For Gehry, 90, the occasion marked a key point in a journey that began more than 15 years ago in Bilbao, Spain, home of one of his most famous designs, an undulating titanium-sheathed museum building on the banks of the Nervión River.

Mayor Jim Kenney with architect Frank Gehry outside of the Philadelphia Museum of Art's vaulted walkway entrance.
HEATHER KHALIFA / Staff Photographer
Mayor Jim Kenney with architect Frank Gehry outside of the Philadelphia Museum of Art's vaulted walkway entrance.

Leaving an exhibition at the Guggenheim Bilbao one long-ago day, the diminutive architect was approached by a tall woman — late Art Museum director Anne d’Harnoncourt.

“She said, ‘Could you imagine doing a building underground and getting as much public buy-in and excitement as Bilbao?’ ” Gehry recalled. “And I said, ‘That would be a great challenge and I could get with it’ — not knowing at all what I was getting myself into.”

For one thing, Gehry was getting into a very long and deliberate process, now led by museum director Timothy Rub, dubbed by Gehry as his “partner in crime.”

The reopening of the north entrance and the northern half of the vaulted walkway (the southern half, toward the Schuylkill, will reopen in a year) is no simple celebration of new doors.

When the core project is complete, visitors will be able to move from the walkway into the main museum via a large open space dubbed the Forum. The now-demolished museum auditorium once filled the Forum space.

The removal of the auditorium — not a part of the original building design — opens up the interior of the museum, allowing visitors to see through the entire building, bringing in light and street vistas through windows, and possibly ending that feeling of being lost amid proliferating galleries of art.

The Forum will provide access to 22,000 feet of new gallery space devoted to contemporary and American art. Those galleries are under construction.

All of that work — in addition to refurbishment of the museum’s west entrance plaza (now closed) and the west entrance lobby, known as Lenfest Hall — will be completed in a year.

The opening-day crowd outside the north entrance prior to the reopening.
HEATHER KHALIFA / Staff Photographer
The opening-day crowd outside the north entrance prior to the reopening.

The key remaining stages of construction include a new auditorium, and the component Gehry is most keen on, the element that d’Harnoncourt used to entice him so many years ago — new galleries for contemporary art dug out of the bedrock beneath the east terrace overlooking Benjamin Franklin Parkway.

The subterranean galleries will be accessed, of course, via the vaulted walkway.

Gehry said that once he got into the project, he realized that Horace Trumbauer and Julian Abele, the original architects, had created a building with “elegant bones that needed to be reawakened."

“We spent a lot of time on the future galleries under the plaza,” he said. “Those galleries are really interesting and could be a spectacular addition. It’s gotta happen. Trumbauer put in all the things necessary to make this work. He even had an opening toward the city from the steps that was in the drawing, the original drawing he had. So we’re following as much as possible his original design, his original intent, and I wish he was here so we could hug him.”