While you were all out day-drinking, the Salesforce Tower construction site was a nexus of major activity on Sunday as an army of cement mixers rolled through to deliver a truly massive amount of concrete for the tower's foundation. Over 18 hours, as CBS 5 reports, 1,300 truckloads of concrete were delivered to the site in order to pour a slab 14 feet thick, forming the base of what will be the tallest building in the western US, at 1,070 feet tall. Developer Boston Properties' construction project director Rob Kain says, "This was one of the largest pours in San Francisco history," and that slab, the height of a double-decker bus, is reinforced with steel rebar as thick as a man's fist.

Construction on the tower began in 2013, but with towers like this, "getting out of the ground" is the part that takes the longest. Now that this slab has been poured, the crew expects to be out of the ground by January, with the tower rising rapidly on SF's skyline throughout the next year, topping off by the end of 2016. Completion of the building is set for 2017.

It will then be San Francisco's tallest building, and will be joined by a whole lot of other tall buildings around the Transbay District in the next couple of years, transforming our skyline in one fell swoop. Salesforce Tower will stand 300 feet taller than our current tallest building, the TransAmerica Pyramid.

Below, the marketing video. Because despite Salesforce claiming a major stake in the building's office space, they've still got a lot left to lease. And click here to see the live construction cam, which shoots images of the site every 20 minutes for an eventual time-lapse.

All previous Salesforce Tower coverage on SFist.