A city design-review board on Tuesday unanimously endorsed Amazon.com’s plan for a five-story office building formed by three intersecting spheres, perhaps the most eye-catching element of its massive, three-block Denny Triangle campus.

Once the city’s planning and development department formally approves Amazon’s application, typically four to six weeks after the board’s approval, a building permit can be issued, city officials say.

Amazon also plans a 38-story tower on that block, which is bounded by Blanchard and Lenora streets and Sixth and Seventh avenues.

Slight changes

The design of “the Spheres” has evolved slightly since August, according to Amazon’s architect, NBBJ.

In the repeating steel module from which the spheres are built, subtle changes now create an effect that “is visually lighter, and geometrically organic and sculptural,” the latest design proposal states.

The spheres still would range in height from 80 feet to 95 feet and feature a mix of flex work space and an atrium of plants and trees.

The area between the spheres and a 38-story office tower would still include a dog park, a walkway and an open field.

Responding to criticism that the public would want to interact with the unique structure, the design presented Tuesday to the review board suggested there would be areas at the private building’s entrances allowing anyone to “experience the Spheres close up.”

The revised design includes a total of 18,000 square feet of retail. The largest space is about 6,300 square feet.

Amazon also added a 5-foot-wide cycle track on one side of Blanchard Street, connecting to the cycle track planned for Seventh Avenue.

Since Amazon’s early proposal for the three spheres was published last spring, the public reaction has been swift and mostly enthusiastic.

“Refreshing”

“Amidst the current building boom of glass boxes and low-rise metal-clad apartments, it is so refreshing to see a design that reaches outside of Seattle for some ‘global’ architectural inspiration, and yet it is well designed and tailored to our own urban environment,” one letter to the design board said.

“These glowing, sculptural orbs will provide an ‘organic’ and very human-scaled focal point to the heart of the high-density Denny Triangle.”

Another letter writer cautioned the city not to push Amazon too hard on designing the spheres to meet the highest goals for “green” buildings.

“Seattle has no shortage of boxy buildings and the recent trend of green engineering leaves the newer ones with busy faces in the name of reducing solar loading,” the commenter said. “I find them dull at best.”

Amazon already has started construction on the first phase of the 3.3 million square-foot campus.

It has not indicated when it may start on the spheres but already has applied for an excavation permit, according to the city.

Sanjay Bhatt: 206-464-3103 or sbhatt@seattletimes.com On Twitter @sbhatt