At a meeting downtown to unveil their plans for Chicago’s latest riverfront skyscraper, architect Jim Goettsch and developer John O’Donnell confronted a public somewhat skeptical of the building’s unusual shape.

“It looks like a giant tuning fork,” said nearby resident John Middleton. Critic Lynn Becker compared it to a punch stamp. At 53 stories, the structure planned for 150 North Riverside Plaza is among the largest developments in Chicago since the recession. But the high rise’s slender footprint and ample green space make it seem delicate next to its bulkier neighbors.

“In some ways it may look counter-intuitive,” said Goettsch, “but it’s an extremely well-designed structure.” With Magnusson Klemencic Associates and Thornton Tomasetti doing peer review, there’s little doubt about its solidity. In fact, Goettsch said during another interview that the concrete-steel composite is fairly conventional.

The form recalls Goettsch’s Sowwah Square, a complex in Abu Dhabi that took home the Council on Tall Buildings’ and Urban Habitat’s 2013 Best Tall Building Award for the Middle East & Africa region. With Sowwah, the clients asked for “iconic” design, said Goettsch, but not a super-tall structure. The end result is a series of towers that appear to have been lifted 10 stories off the ground, opening up to a shared plaza.

Goettsch reprised the solution in Chicago for entirely different reasons. Vacant for decades, the site is divided by railroad tracks. Amtrak owns the farthest west parcel, and has a permanent easement on the city-owned middle parcel. That leaves only a small riverside plot for O’Donnell’s 1.2 million-square-foot office building, especially since the law curtails development within 16 feet of the tracks’ centerline, and within 30 feet of the river. O’Donnell bought that parcel in December 2011 for $12.5 million and later negotiated for air rights over Amtrak’s property.

Earlier proposals called for two towers, sharing several stories of parking. Once a scaled-back development satisfied his calls for a riverwalk and park space, Alderman Brendan Reilly handed over the city-owned parcel. The alderman rejected requests for tax increment financing. “We’ve essentially capitulated to everything [Reilly] wanted,” said O’Donnell.

Out of that wrangling came a substantially leaner footprint, totaling one tower and just one story of parking with 81 spaces. The garage will be covered over with a park that gently slopes up to the west, ending with a glass railing roughly 13 feet above the adjacent alleyway.

“There was a concern that what we were doing was very corporate,” O’Donnell said. So the design now vies to achieve an effect that O’Donnell called “Millennium Park light.” As the building tapers toward its base, it makes way for a glass cable net wall enclosed lobby that opens to the west. It also leaves room for a grassy hill, scalloped with curvilinear walkways.

“It’s like a ballerina,” said landscape architect Ted Wolff. “It’s a muscular building, but it’s on point.” Tree-lined walkways traverse the site north to south on either side of the building. The riverfront path jogs east as it passes beneath the structure’s elevated mass. Although the southeast corner features a small landscaped amphitheater meant to focus attention on the river itself, all interaction with the river is from street-level. Dock-level facilities like a fitness center and a white tablecloth restaurant enjoy views but no direct access. Still, including street crossings and stairs, there could be a continuous riverwalk from the building’s northern neighbor, the planned River Point development, south to the former Chicago Daily News building.

The building’s facade also draws inspiration from the river. Weary of overly reflective glass towers, Goettsch Partners dialed back the exterior reflectivity to between 15 and 25 percent. Mullions project between 6 and 17 inches to form undulating fins that mimic the visual effect of wind on water. Amid that wave-like shape, columns spaced every 30 feet lend texture to the glassy expanse.

“There are relatively few sites downtown as visible as this,” said Goettsch, “and that visibility I think brings with it a certain obligation to do something that’s worthy of that kind of site.”

Still awaiting tenants, the building could break ground in mid-2014 and wrap up 28 months later.