On the catwalk suspended a hundred feet above the arena floor at Verizon Center, where you look down on the giant scoreboard that hangs over the void, the air smells like cigarettes and the atmosphere is eerily calm.

Calm, that is, if you’re one of the riggers hanging equipment for the Jennifer Lopez and Enrique Iglesias concert last Saturday. But if you’re an average mortal, you are not calm. You are starting to pant. The abyss presses in; the only thing between you and a 10-story plunge onto concrete is an open metal handrail on either side of what feels like a footbridge to a heart attack.

Better to focus on the riggers. Trussed up in harnesses that triangulate around their hips, they look like superheroes in cargo shorts. They are forbiddingly cool as they take a break before getting back to hauling up chains. One is so cool, in fact, that he’s napping on a pile of the burlap scraps he’ll use later to pad the beams. Another rigger leans over the railing as he smokes, casually flicking ash into the emptiness.

A man the size of a linebacker strolls jauntily across the catwalk as if he were ambling down the street on the happiest day of his life, the harness forcing his legs wide so that he bounces and rolls a bit from side to side.

Draped in coils of red rope, Phil Vasko brushes past with a greeting and a big grin. “You’re not leaving the best office in the city, are you?” he asks.

Muffin Brennans handles wires that power a light high above the stage at the Jennifer Lopez/ Enrique Iglesias concert at the Verizon Center on July 28, 2012. (Daniel C. Britt/THE WASHINGTON POST)

This nosebleed summit, the best office in the city?

“It is to me!” he calls over his shoulder as he prepares to step off the catwalk and onto one of the beams tucked under the arena ceiling. Sure, for a certain wing-walking, rush-addicted mindset, it’s a lovely office indeed: mere inches of steel, lots of air.

By the time Lopez and Iglesias start their soundcheck several hours later, 136,000 pounds of speakers, lights and video screens will dangle over the singers’ heads. Each piece will have been guided into place by “upriggers” like Vasko, who creep along the beams to secure cables and chains, and “downriggers” on the arena floor who attach the equipment.

Rigging a rock concert has always been hard physical labor. But as shows get more technologically complex, they require ever more intricately coordinated manpower. With two artists teaming up for this tour and each aiming for a separate spectacle — one production staffer calls the J-Lo/Iglesias alliance a “battle of the bands” — there’s a lot of gear to hang.

Later, Lopez will cha-cha and gyrate impressively in her hour-long set, scampering up custom-built stairs and ramps in her stilettos, backed by an energetic team of dancers. But they will have nothing on the raw power and behind-the-scenes choreography of the riggers, carpenters, stagehands and loaders that started heaving her followspots at 4 a.m.

There is a truth acknowledged with some irony by veterans of the road: “People come to see a show, not hear a show,” says Omar Abderrahman, the tour’s production manager. He got his start as a rigger in the late 1970s, the era of REO Speedwagon and the Cars, when no one wore a harness and speakers were stacked on the floor.

That’s not good enough for the arena concerts now. In roadie-speak, the Lopez/Iglesias tour is known as a heavy show. Eighteen trucks transport 80 crates of instruments and 1,500 cases of lights and other equipment to each venue. Once they pull up to the loading dock, a construction site unfolds, with separate spheres of action. There are three stages to build, trusses to construct, two video systems to assemble, dressing rooms to set up with wicker furniture and J-Lo’s crystal-encrusted costumes.

After the show, every last element will be swiftly broken down, packed away and loaded back on the trucks. In the space of 22 hours, a multilevel monument to sensory overload and celebrity adoration will be built and unbuilt.

It takes a cast of 100 to do it.

6:30 a.m. on the loading dock: Forklifts zip by, heading into the arena. Loaders follow, leaning into the boxes and carts they’re pushing. Two guys pick their way through the stream of motion like something out of a vaudeville routine, stepping gingerly as they guide lengths of metal trusses bridged across their shoulders.

“Make way for Enrique’s mirror ball!” A clutch of workers scoot past, wheeling the glittering orb in a hamper, nestled in blankets like a giant ostrich egg.

Even the hardened local crew members, Verizon Center regulars from the International Alliance of Theatrical Stage Employees union, are awed at the ball’s planetary size. “Look at that [sucker],” marvels one.

The ball will spin for just one song, as Iglesias croons his soft-rock hit “Hero” to the flabbergasted female fan he pulls onto a platform, at the far end of the arena from the main stage. The two will slow-dance and cuddle as the mirror ball turns the giant space into a swirl of starlight. Travis Shirley, Iglesias’s production designer, calls it “the high-school prom moment.”

But there’s a lot to do before that kind of magic can happen. Inside the arena, Art McConnell, the tour’s head rigger, has been marking equations on the floor in chalk, figuring out all the spots on the beams where he needs a motor to hang. With all the video screens involved, he has more than 100 points to calculate. (Geometry refugees: This is where the pythagorean theorem comes in handy.)

Within an hour, the floor is crawling with downriggers carrying ropes and chains, craning their heads back as they look up. Because the real show is high above. You need binoculars to see it; scanning for upriggers in the shadowy heights is a particularly elusive form of bird watching.

There’s Steven Eajewski, beam between his legs, tattooed calves and boots dangling free. As a length of cable rises up to him, he stretches out across the beam to grab it, part Peter Pan, part gymnast. Except there’s no net.

The air rings with the wind-chime tinkle of chains. Bits of burlap tied to the dangling ropes fly upward like whimsical little ghosts. Soon thin cables replace the ropes, forming what looks like a curtain of spider’s silk over the floor. What had been a chaos of shoving and unpacking resolves into a crisp vertical current of lift and descent.

A new wave of activity sweeps in. Time to build the trusses that will hold the lights and video screens. The floor under the cables fills with rows and rows of metal parts, piled up like a black coral reef. But with improbable smoothness, in a matter of minutes clean modern architecture emerges as 15 people form an assembly line to construct a vast lighting grid.

With a momentous rattling sound, the grid levitates, and the workers regroup to screw on lights and the horizontal expanse of Iglesias’s video screens. These screens are the singer’s answer to J-Lo’s extravagant and unmatchable physicality.

“Jennifer Lopez is working with dancers and choreography,” says Shirley, the production designer. Black studs twinkle in each earlobe, and his boyish face is crowned by a stylishly unruly cowlick. “With Enrique, we didn’t want to just be a band on the stage. We wanted to find a more masculine way to create the same level of spectacle.”

The designer countered Lopez’s lusciousness with a towering man-cave of video screens, which wrap around Iglesias’s set and project bright geometric patterns that pulse on the beat.

Like they say, without lights it’s just radio.

Not to be outdone, Lopez has her own wall of vertical screens that turn her stage into a self-marketing temple, beaming close-ups of her lips and smoky eyes and shots of her snuggling with her beau. (They are a poor substitute — no matter how photogenic, the pixelated Lopez can’t match the energy that emanates from the fleshly one.)

10:30 a.m. Surveying the hive of quiet industry as riggers set up the dueling sets of screens, Abderrahman, the production manager, is a model of calm. “They don’t pay us any extra to panic,” he says. Set this sprawling show up in a day? No worries. Rod Stewart and Stevie Nicks played Verizon Center the night before, meaning the Lopez/Iglesias roadies had to wait until the local crew had packed up the “Heart and Soul” gear, which took until 2 a.m. Some of the same workers came back two hours later for this load-in.

It’s not only the screens that make this show a bear to set up. It’s the stage space, all those platforms for the dancers to stomp and spin around on. That’s largely a phenomenon of the female pop star, says Abderrahman. (Although he calls them, charmingly, “the gals.” The female riggers are gals, too, as in: “When I started out, we had no gals. Now there’s a lotta gals. Or some gals.”)

Tina Turner, Cher, Britney Spears: They all helm big production shows. “Madonna, now, she’s at the top of the heap,” he says. “She does the biggest and most expensive shows, with videos and elevators and hydraulic lifts.” How big? Some 160,000 pounds big.

Hydraulics can be tricky. Abderrahman recalls a Cher tour he worked on when the star got stuck on a 10-foot-tall pedestal because the computer system that raised and lowered it crashed. While waiting for it to reboot, Cher — “a real pro” — calmly told the audience jokes.

Back in the day, arena shows could be packed into three or four trucks, as it was with Jethro Tull, the first tour Abderrahman worked on nearly 30 years ago. U2’s “360” stadium tour, with its portable outdoor roof modeled on part of Los Angeles International Airport, is “probably the biggest rock show on the road ever,” he says. It’s so big that instead of one caravan of trucks traveling to each venue, duplicate sets fan out to various cities at once to set up in advance.

Abderrahman grew up in showbiz: His Moroccan grandfather and his father were acrobats; his mother was a trapeze artist. As kids, he and his brother had a trampoline act. When he left home, stepping onto the beams as an uprigger felt natural. But in the days before harnesses, he watched people fall — and die.

It’s still a dangerous business. “If one guy uses a wrench, sets it down on a speaker and it goes up in the air and falls, it can kill someone,” he says.

Concurs one of the stagehands, who asked that his name not be used, “If somebody yells ‘Heads up,’ don’t look up. By the time you do, you’re dead.”

But if the trend to heavier shows means a lengthier, more complicated setup, it also means more employment, a plus noted by several crew members. With this concert capping a streak at Verizon Center that included Cirque du Soleil, Roger Waters and the “How to Train Your Dragon Live Spectacular,” they say this has been the busiest July in memory. (Could rock shows be an economic indicator?)

Eventually, a bulky, blocky village of equipment rises several stories into the air. At the other end of the arena, carpenters have been sledgehammering flooring into the metal supports of the stages. The “toasters” — little plexiglass elevators that will pop two of Lopez’s dancers into the air from underneath — have been built, along with the thrust stage that both Iglesias and Lopez will prowl to get closer to their fans. At about noon, an army of stagehands forms along the outer edges of the massive platforms to roll them under the expanse of lights. The workers brace, tilt, dig in with their boots and slowly, with rough grace, a continent of sleek construction slides into its new geography.

Much later, after the last fireworks explode, after the dancers turn their final flips, after the confetti falls, this vast, towering, temporary world dissolves. It happens in double time. The white satin bunting that trimmed the stage is ripped off and dumped into bins, the speakers are lowered and unhooked, the stage is rolled backward to be broken up. A guy rides a forklift like he’s the Snow Queen, gliding through drifts of confetti to pick up carts stacked with folding chairs.

Downriggers pack the chains into crates. The scraps of burlap flutter down on their ropes. Far overhead, where the air is smokier now from the pyrotechnics, the upriggers walk the beams, enjoying a few more hours in the best office in the city.