Now hanging, as of Wednesday, in SFMOMA's Third Street atrium — a.k.a. the museum's former main entrance — is a monumental abstract painting by artist and MacArthur "genius" grant recipient Julie Mehretu that spans two canvases, and was commissioned specifically to fill two large walls flanking the central stairway that previously featured works by Sol Lewitt and others.

Like the new Howard Street atrium entrance, this atrium is free to enter to the public.

The time-lapse video above, shot for the SF Chronicle, shows the hanging of the second canvas on the right-hand wall, just after Mehretu's work arrived. Each canvas measures 27 feet by 32 feet, and they will be on public view in their current form before being properly stretched and framed in place for their official unveiling on September 2.

As the Chronicle reports, the process of hanging the canvases was not a simple one:

Each canvas weighs about 300 pounds, and while still rolled up was lifted into place by a chain hoist hand-cranked from two floors above. Once there, it was stapled at the top and ever so slowly unrolled by six crew members on three scissor lifts that drop in synchronized time.

Later, once acclimated, it will be stretched and stapled, then fitted with a wooden frame that comes in eight pieces and weighs more than the canvas. Mehretu will then fly out to oversee the lighting.

Museum director Neal Benezra knew he wanted something specific, huge, and striking for the atrium space, and he says he found it in the 47-year-old, Ethiopia-born Mehretu's work. After seeing her largest work to date, an 80-foot-long, 20-foot-high mural at Goldman Sachs' headquarters in Manhattan, he knew he had found an artist who could "rise to the occasion" of this commission.

Diversity likely played a role in the selection as well, following some criticism the museum received after the art community last year learned of some stipulations that came with the long-term loan of the Fisher Collection, which is heavily dominated by white male painters of the 20th Century.

"I can’t think of a larger painting made by a woman for a public space in the history of art," Benezra said proudly to the Chronicle.

The work is called "Howl eon (I,II)," and it's taken Mehretu nearly a year to complete it. She began by having several landscape paintings, including Albert Bierstadt’s Lake Tahoe (1868), inkjet-printed onto the canvas, and then overlaid with images of modern race riots and protests blurred through Photoshop. Benezra describes her process saying, "She works the surface; she erases and adds."

Speaking to the New York Times about the piece earlier this month, Mehretu said, "Eighty percent of the marks I put down I wipe or sand away."

She said she was inspired first by the soaring nature of the space, which made her think of majestic 19th century landscape pieces, and then by the state of the country shortly after the November election. "I was attracted to these landscape paintings that were trying to describe a really intense moment historically, of what this country was becoming, on all these different levels... But at the same time this was a landscape of horror."

The resulting abstract work is very different in mood, shape, and color from the Goldman Sachs commission, which you can see her working on in the Art 21 video below. She calls it "my most American painting."

"From a distance you have one experience [of the painting], and you have a different experience up close, but they don't battle each other," Mehretu says of that 2009 work, titled Mural.

Previously: Regarding The Potentially Dicey Stipulations In SFMOMA's Agreements Surrounding The Fisher Collection