Heather Larsen has slacklined some intimidating heights, balancing, twisting and even bending into yoga poses on narrow webbing stretched between cliffs and over canyons.

But Monday’s morning tippy-toed walk across a 20-meter-long line situated 30 meters (almost 100 feet) above the ancient stones of Jerusalem’s medieval Tower of David Museum, was Larsen’s “most historical” walk yet.

“This one is pretty much at the top of the list at this point,” said Larsen, who has also highlined in Tasmania and Bosnia, in addition to locations in her home state of Colorado.

It wasn’t the first time a tightrope walker toed a line in Jerusalem’s Old City. The last time was in 1987, when Phillippe Petit, whose Twin Tower act was chronicled in the 2015 film “The Walk,” walked a slackline pulled taut between buildings situated in the Arab and Jewish Quarters.

Slackliner Heather Larsen making her way between two ancient citadels at Jerusalem's Tower of David Museum on May 2, 2016 (Jessica Steinberg/Times of Israel)

Slackliner Heather Larsen making her way between two ancient citadels at Jerusalem’s Tower of David Museum on May 2, 2016 (Jessica Steinberg/Times of Israel)

That time, the high-wire stunt helped launch the annual Israel Festival, three weeks of cultural performances that take place in Jerusalem each June.

This time, Larsen’s balancing act was filmed as part of an upcoming crowdsourcing Kickstarter campaign for Joey, an Israeli-designed urban backpack created by local company Koala Gear.

“We’re looking to create better balance with our bag, and we needed someone who knows what balance is,” said Yonatan Aldouby, one of the three Koala Gear founders. “Heather’s whole life is about balance.”

Larsen is recognized as one of the world’s top female highliners, a pioneer in the height-defying sport.

In the Old City, the lithe, tanned figure sporting a bright coral tank top and turquoise leggings, with her white-blonde hair swept up a high ponytail, made her way along the narrow length of slackline strung between the squared, stone crenellations built by King Herod and Suleiman the Great — battlements once used for sentries standing guard. On her back, for at least one of the balancing acts, was the black Joey backpack.

Heather Larsen, a world-renowned 'slacker', whose highline tricks brought her to Jerusalem's Tower of David Museum to help promote the 'Joey' bag, designed for better body balance (Jessica Steinberg/Times of Israel)

Heather Larsen, a world-renowned ‘slacker’, whose highline tricks brought her to Jerusalem’s Tower of David Museum to help promote the ‘Joey’ bag, designed for better body balance (Jessica Steinberg/Times of Israel)

Larsen, who lives outside Denver, Colorado, works in corporate finance and is a so-called “slacker” in her free time, an athlete who balances and performs tricks on a narrow web line stretched between two points. When she’s practicing or training someone at home, she often heads to a local park and positions a line between two trees, balancing a few feet above the ground.

“You want to practice on something shorter, so there’s no consequence if you fall,” said Larsen.

Her preference, however, is at the mouth of a canyon near her house, hundreds of feet above ground, as she highlines — toeing, balancing, and often standing on one hand or foot — while connected to the line by harness. When she does slip, and it happens, there’s a sharp snapping sound from the harness attached to both walker and wire that elicits gasps from the crowd, and just a wry grimace from Larsen.

“This sport is a lot about community,” said Larsen. “Even if you watch someone struggling on their first climb, it inspires you to try harder.”

When the Koala Gear team contacted her about coming to Israel to be filmed for their Kickstarter campaign, Larsen said she couldn’t resist the offer.

The entrepreneurs, a pair of students and one fashion designer, had been looking for someone who represented their own search for balance, a concept they considered seriously in their urban bag project.

The company was initiated by Aldouby, a student at Jerusalem’s Shalem College who has tinkered more than once in industrial design, and turned down an acceptance at Jerusalem’s prestigious Bezalel Academy of Arts and Design.

He now dabbles in design in his free time, and working with friends and partners Andreas Lanz, a Swiss marketing strategist and PhD candidate and Efrat Michman, a fashion designer, the three tried to create the perfect backpack — an urban, functional bag that can balance both daily and travel needs, without the unattractive straps and zippers that clutter most knapsacks.

Yonatan Aldouby, an entrepreneur who brought highliner Heather Larsen to Jerusalem in April 2016 to demonstrate the balance he strove to create in his Joey backpack (Courtesy Yonatan Aldouby Facebook page)

Yonatan Aldouby, an entrepreneur who brought highliner Heather Larsen to Jerusalem in April 2016 to demonstrate the balance he strove to create in his Joey backpack (Courtesy Yonatan Aldouby Facebook page)

“We wanted something that wouldn’t hurt your back, but that would fit your laptop and everything else people shove into their bags,” said Aldouby, who is 27.

For his Swiss partner, Lanz, the bag had to be functional but stylish, challenges that their third partner, Michman, could handle in her design.

The Koala Joey, named for the poach-dwelling marsupial, is made from black leather or a cushy, black lycra-like fabric, and is tall in appearance, with a reinforced laptop section as well as an extendable section on the top of the bag for carrying extras, like clothing when traveling or groceries from the store. Aldouby said his wife used only the Joey bag for a recent two-week trip in Italy.

It took nearly a year of work to design the right prototype, said Aldouby, who researched backpacks extensively in European markets and had the bags manufactured in China.

The Kickstarter campaign, which will be launched in the summer, and which they hope will raise at least $30,000, will offer 100 bags for $100 during the first 60 days of the campaign, but they hope to keep a modest price point for the backpack, keeping it at $150 in the future.

“We’re all about finding the balance,” said Aldouby, while overhead, against the bright blue sky, Larsen completed her final web walk of the morning.