The song, the voice were unmistakably familiar.

The source, though, and the sound just didn't seem right.

New state-of-the-art speakers had been hung from the Wells Fargo Center rafters just the week before, the latest of the additions and alterations  to the 22-year-old building over the last few years. But this music traced back to a scratchier time, when Kate Smith performed live for Flyers fans, their secret weapon used to fend off challenges to their supremacy.

The source, detected after turning a bend of the revamped mezzanine last week, came from a construction worker's boombox. A smile on his face, a bandana around his scalp, the owner was singing along with Kate, his rendition more enthusiastic than recordable.

"A project like this, they really care," Phil Laws,  the vice president of operations for the Wells Fargo Center, said later. He has overseen the ambitious rebuilding that began before the Democratic National Convention two summers ago. The work  will cost in excess of $250 million by the summer of 2020, when they turn the top rung of the building into a millennial-oriented meet-and-eat, and create some yet-to-determined ice-level experience as well.

"I mean, everybody's a professional, and I'm sure they do their job anywhere," Laws said. "But I think in that Kate Smith moment that there's something beyond professionalism. That looked awfully joyful to me. That's a homestretch move."

In truth, there is no real homestretch to completely redoing the place, a reality to which Laws long ago conditioned himself. "The elephant gets eaten one bite at a time,'' he is fond of saying, a mantra that informs his approach. This summer's upgrades built upon last summer's upgrades, and further upgrades are due next summer as well.

But the jewels of the redesign – the opened ends of the arena to offer a more expansive viewing concept, the sound and lighting systems that will transform the acoustics and visuals, and finally the glass windows that will both dramatically change the façade and provide a view of the expanding city skyline – that's the present homestretch of which Laws speaks.

>> READ MORE: From CoreStates to Wells Fargo — 20 years of history of the South Philly venue

On Thursday, workers began to replace the outside wall with sheets of glass, a one-step process that was the culmination of months of grinding, grueling, interior prep.

"This has been a centerpiece of the design from the beginning,'' Laws said of the windows. "The question has always been: Can we make this work? We're at that point where all that's happening. The walls are coming down. The glass is going in. I can see our vision now.

"That's what I'm excited about, to finally be able to share that vision."

This is some of what Flyers fans will see when the Flyers host the Islanders for a preseason game on Sept. 17:

  • Corridors doubled in width, providing an exponential increase in food and drink choices, many from Philadelphia's restaurant and craft beer scene;

  • Gray seats throughout, replacing the red scheme that was carried over from the Spectrum 22 years ago;

  • Sections 219 and 207, at each end of the arena, will open to provide a full view of the game below for fans seeking food and drink. Large HD screens in those widened corridors will ease anxiety over missing action while getting a bite or quenching one's thirst, and expanded points of sale should expedite that pursuit.

  • And, of course, the city's skyline through those glass windows along the building's north wall, a pricey aesthetic alteration of which Dave Scott, the chairman and CEO of Comcast Spectacor, has said, "We just felt like we had to capture that view. A lot of people don't have our view."

Years in planning, the view will be created in just two days. Because the building has been in use throughout the gutting and redesign, glass will immediately be installed following the punch-out of each panel of outer wall. Indeed, Law's elephant approach is not just a mental health approach – it's a practical one.

"I don't know if you could do a project like this 30 years ago the way we're doing it,'' Laws said. "The pace of everything is different now, like any business. Just managing the supplies, the just-in-time deliveries. We can't have 500 yards of pipe laying around the day you're putting on a concert. We have to get it only at the point we need it.''

That turns the electricians, carpenters, plumbers, et al. into more than just workers. There's an athleticism involved as well as a pride in ownership.

"This is much more interesting to them than an office tower that they build and never go in,'' Laws said. "A lot of these guys are fans. Even in the earlier stages of the product you will come across people, electricians, say, who will tell you that they worked on the original project."

Even people who have at least one Kate Smith song on their work playlist.

Laws became a first-time father a few weeks ago, amid the final summer surge of activity. He admits it has made his one-bite-at-a-time process harder to uphold, made it harder not to think farther into the future than the job allows.

"Every now and then you will open up a wall from the original construction and see someone's signed name,'' he said, smiling. "And these guys are doing it now. They're leaving, in some secret corner, their initials or signatures. So that someday they bring their kid, or an unborn kid, back some day and say, "Behind that tile, my name is written.' "