Weeks after Pope Francis paraded past adoring throngs along Philadelphia's premier boulevard, a new frenzy has taken hold on the Benjamin Franklin Parkway.

Towering cranes, traffic detours, and construction fences have created a Legoland out of Logan Square, whose Swann Memorial Fountain forms the heart of the majestic avenue connecting City Hall and the Philadelphia Museum of Art.

All around the fountain, apartment towers rise, workers topple Vine Street Expressway bridges only to build them back up, and old buildings make way for new hotels. That doesn't even count the face-lift for LOVE Park that is to begin next year.

Two years shy of its 100th anniversary, the Parkway is experiencing a degree of investment and construction unseen in generations.

"Look at where we are," Deputy Mayor Michael DiBerardinis said as the longtime Parkway booster sipped coffee recently at a Parkway cafe. "It's an amazing transformation."

Most people will notice first an $80 million project to upgrade I-676 over the next four years.

After a halt in work to allow for Francis' visit, reconstruction ramped up in late September.

Seven bridges are being replaced above the expressway, a subterranean artery begun a decade after World War II.

Detours and intermittent street closings will be commonplace as intersections that serve as highway bridges are replaced through 2019, said state Department of Transportation spokesman Gene Blaum.

Crews recently shut down some of the Parkway's inner lanes nearest Logan Square and narrowed other streets, said Dave Warner, project manager for PennDot contractor Buckley & Co.

In recent weeks, city and police officials met to coordinate communications to minimize the disruption. A priority is to allow generous access to the Parkway's museums, concerts, and parades.

"All this great and exciting work is going on," said DiBerardinis, who as the deputy mayor overseeing the Department of Parks and Recreation attended that meeting to answer the question: "How does the life of the city continue as this project moves forward?"

The message to all agencies, according to Mayor Nutter: "Just make it work. Be creative. Figure it out.

Much highway work will be noisy and done at night, said Drew Murray, president of the Logan Square Neighborhood Association.

"I wish we could snap our fingers," he said, "and it could be done."

The Parkway also is crackling with projects that have come together about 15 years after civic activists first prodded leaders to consider improving the 1.5-mile-long boulevard.

City, state, and philanthropic dollars totaling $20 million laid the groundwork in 2008 for today's building frenzy by underwriting improvements that removed driving lanes from the Parkway, added bicycle lanes, replaced sidewalks, and more.

The opening of the Barnes Foundation building in 2012, which brought a world-renowned art collection to the former site of a juvenile justice center, fueled momentum.

"All of what's going on the Parkway, all of the infrastructure development, is possibly the most public demonstration of why government in infrastructure leads to significant private development," Nutter said.

The projects are large and ambitious.

Spoking off the Swann fountain at One Logan Square is the renovation of the former Four Seasons Hotel. Workers are converting it to a luxe brand, the Logan, to open next month. New owners are crafting a rooftop bar on the ninth floor that will offer panoramic views of the Parkway.

Across the traffic circle at 1801 Vine St., New York developer R. Donahue Peebles is pursuing historic-tax-credit financing to convert the vacant Family Court building into a grand hotel, according to the Commerce Department. The $85 million project envisions 199 rooms, a 3,500-square-foot ballroom, meeting and board rooms, a spa and fitness center, and a restaurant and bar.

On 21st Street a block north of the Parkway, developer Neal Rodin's $140 million Whole Foods store and 293-unit apartment tower are rising.

On the 1700 and 1600 blocks of Vine, scaffolding draws the eye to two spires of a new Mormon temple, slated to open next year with a two-story meetinghouse. A 32-story apartment tower, 13 townhouses, and retail stores should be finished in 2017, church spokeswoman Corinne Dougherty said.

Construction bids are being sought to start building two playgrounds and a "sprayground" on the edge of Von Colln Memorial Field at 22d Street and the Parkway. The $2.4 million project, funded by the city and the William Penn Foundation, is to be finished next fall.

Plans are in the works to build a plaza, fountain, and venue for outdoor movie nights, poetry readings, and jazz concerts along seven city-owned grassy acres in front of the Park Towne Place apartment towers near 22d and the Parkway.

In April 2016, the city will demolish and rebuild LOVE Park, a $16.5 million venture to be completed in June 2017.

"It's just amazing how much energy and focus and money is around the Parkway right now," said Mark Focht, who is in charge of capital projects under DiBerardinis.

This was unimaginable only a few years ago.

Completed in 1917, the Parkway was intended as a verdant expanse connecting City Hall to the vast acreage of Fairmount Park, a diagonal flourish in the dense industrial grid of the city.

Five grand buildings rose swiftly: the Philadelphia Museum of Art, the Rodin Museum, the Franklin Institute, Family Court, and the Free Library of Philadelphia.

But the Parkway did not live up to its promise. The Depression helped damper the construction of additional cultural attractions.

And then there was the issue of cars.

"There were two kinds of automobile assaults on the Parkway: cars traveling down it, and the Vine Street Expressway cut underneath it," said David Brownlee, an architectural historian at the University of Pennsylvania.

The 1950s-era expressway was city planner Edmund Bacon's effort to "rescue" Philadelphia from the flight of residents to the suburbs by enticing them back, Brownlee said.

But it was not built as a tunnel. And that left gaping holes in what had been uninterrupted Parkway streetscape.

"It was one of the things that made the Parkway so unlovable," Brownlee said.

Never mind crossing the broad thoroughfare on foot. It was so hazardous, it became a punch line.

The release in 1976 of Rocky, with its iconic scene of Sylvester Stallone running up the Art Museum steps, brought romance to an avenue otherwise scorned for not having become the city's Champs-Élysées.

But it was not until the late 1990s that civic voices led by the Center City District joined to call for change to the Parkway.

And in 2008, with former Mayor Ed Rendell in Harrisburg as governor, DiBerardinis a cabinet secretary, and Nutter as mayor in City Hall, pivotal funding was in place to make the Parkway a safer, prettier place, even as the global financial crisis took hold.

That year, Center City District completed construction of Cafe Cret at 16th Street and the Parkway. The street itself got a makeover, too.

In 2012, the CCD opened Sister Cities Park, with an adjacent cafe, off Logan Square. The Barnes opened that year, too. Planners also began a yearlong effort, "More Park Less Way," to imagine improvements that did not resort to retail and residential development, a proposal earlier put forth by the CCD.

The commercial real estate boom that has swept central Philadelphia and University City over the last several years also has served to bring considerable private capital to the Parkway.

All of this amazes Focht and many others. "It's the largest transformative time in the history of the Parkway since it was completed in 1917," he said. "It could not have been foreseen."

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