To celebrate their progress and also remind us that this Transbay Transit Center thing is really happening, Darin Cook, a senior associate principal with designers Pelli Clarke Pelli Architect, led the big reveal yesterday. For a crowd of VIPs including House Minority Leader Nancy Pelosi, he and his team showcased a hunk of what will be the building's perforated metal skin.

The metal covering, an alternative to glass, comes at a savings of $17 million. That can't hurt: The project' phase one price tag has ballooned to $2 billion, according to the Chronicle, and of course there's some confusion as to who, exactly, is financing phase two.

Awning Unveiling

Today, TJPA was joined by House Democratic Leader Nancy Pelosi, Supervisor Jane Kim, Chairman John Burton and Mitchel Kettle from Ironworkers Local 377 to unveil the unique awning of the Transbay Transit Center. The awning features the never-repeating Penrose pattern, which was discovered by physicist Sir Roger Penrose and will teach visitors about math and science. #milestone #transbayawning

Posted by Transbay Transit Center Project on Monday, March 7, 2016

"This is a single panel. The next step will be to fabricate and connect 18 of them," the architect announced. "This will give us a chance to look at every detail before the fabricators go hog wild.”

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Penrose Rhombus Tiling, the continuous pattern on the 6-by-6 panel displayed above, was discovered in 1974 by Oxford mathematical physicist Roger Penrose. Its holes, like those on paper snowflakes, will allow light to shine into the transit center — a hub of eleven transportation systems from buses to rails — when it opens late next year.

Previously: Checking Back In On The Transbay Transit Center, And Its Shiny Metal 'Skin'

Rendering via Pelli Clarke Pelli