This May, eight orangutans will move into their new home at the Indianapolis Zoo, where visitors will have a rare chance to get up close and personal with Asian great apes by literally hanging out with them. Workers are busy putting the finishing touches on the zoo's $26-million International Orangutan Center, which houses three buildings and 11 surrounding towers connected by a roughly 80-ft-high aerial cableway that allows the apes to move around the 2-acre exhibit and swing high above viewers. The project also includes a 60-ft-tall suspended gondola ride spanning 1,000 ft around the perimeter of the site, where visitors will be able to view the orangutans up close from the air.

A typical orangutan—the name in Malay translates into "person of the forest"—needs regular upper-body exercise to stay fit, and the exhibit aims to preserve the endangered species by stimulating the animals physically and cognitively. "We had to design a facility that let people get to know orangutans the way those of us who work with them know them," says Rob Shumaker, the zoo's vice president of conservation and life sciences. "Orangutans are perfectly adapted for living in the trees, so we had to give them spaces that function just like trees." The design team, led by local architect Browning Day Mullins Dierdorf Inc., decided early on to use modern materials to mimic the environment of a forest—without trying to fake the look of the real thing. "Oddly enough, there aren't a lot of facilities that promote that," explains Jonathan Hess, president of BDMD. "So, the exhibit started to get taller."

Inspired by Indonesian architecture that Westerners may mistake as church-like, Hess envisioned a two-story exhibit building, roughly 19,000 sq ft in total, that allows the apes to climb inside a climate-controlled day room up to 42 ft high. A 2,800-sq-ft glass curtain wall cants away from the space 20° from vertical to allow apes to sit in the window wells over viewers on the plaza below. Steel, concrete and embedded windows frame the remaining interior spaces, while a lighted, steel spire rises above the building's green roof to a tip height of 150 ft. Through secure outdoor yards and the cableway, the orangutans can also visit two smaller satellite buildings, covering about 800 sq ft each.

Before breaking ground in December 2012, Turner Construction Co. held value-engineering sessions with the owner and designers. Tubular steel slated to frame out the interior spaces changed to cold-formed steel, which was deemed less expensive yet still functional.

Such cost-cutting exercises helped the team mentally prepare for a jigsaw puzzle of materials and shapes. The day room's steel starts with two long spines—each runs 125 ft down the center of the building and fans out diagonally into ribs that join up with glue-laminated timber roof beams that protrude past concrete exterior walls. The steel ribs then drop down diagonally between cast-in-place, concrete wall panels. "The steel, the complexity and coordinating that on site was, in my mind, one of the toughest things to do," says Sam Sharp, project manager for Turner, the zoo's construction manager. "You've got a number of building materials all coming together in the same location, with walls on 70° angles that are 100 ft high."

Aside from the tight site hemmed in by an actively operating zoo, the builders reconciled the commingling of materials—few of which meet at perfectly square right angles—by holding weekly coordination meetings aided by a 3D design model that BDMD shared.

"We had a fair amount of GoToMeetings, with the architect running a model in his office and us sitting here on the phone with the same thing flying around on the screen," says Nick Waters, superintendent for Turner. Subcontractors in charge of the steel, wood and curtain wall pieces built their own detailed models for fabrication. Meanwhile, local concrete subcontractor Midwest Constructors LLC had the hard job of modeling the day-room walls in the real world. For example, vertical pleats in the concrete required custom equipment. "All the formwork was hand-pieced in the field," says Neal Burnett, president of Midwest. "We had to use a lot of heavy bracing" to resist the hydraulic pressures at the saw-cut seams, he adds.

Another layer of complexity was discovered in ape-proofing the windows cast into the interior walls, along with any other exposed hardware. "Every single nut in the facility has to be secured," Shumaker explains. "Anything that's within reach of the apes has to be incredibly durable." Orangutan hands are quite large—as much as 18 in. from palm to finger—yet amazingly dextrous, he says. Though some team members were dubious of the risks at first, the workers became accustomed to tack-welding fasteners or using industrial-grade threadlocking fluid to keep the hardware safe from prying hands.

Also thinking ahead, workers pre-assembled the 90-ft-long, triangular spire—dubbed the Beacon of Hope—and wired it before hoisting. "It saved us an enormous amount of time by not needing a lift in an area already consumed by lifts," Waters says. Guided by touchscreens, the orangutans are being trained to light up the spire each night, and a timer will shut it off around midnight to keep migratory birds clear of the building.

Although not immune to change orders or requests for information (RFIs), the project is proceeding on time, on budget and without any lost-time injuries. "As complex as this building is, I think we've really minimized the number of RFIs," says Wade LaRoche, Turner senior project manager, who notes that he cannot think of a comparable project in the company's deep portfolio. Teamwork has been key. "I don't think this ever could have happened without that level of collaboration with all parties," he says.