What is the biggest building in Tennessee? Obviously, this blog post will be dated at some point, likely in the not-so-far future. But I have at my disposal, after several hours of processing a huge geojson of data, courtesy of Microsoft, the building footprints for Tennessee in an easily digestible GIS format. It turns out the GM Spring Hill Plant is the largest building, weighing in at approximately 5,942,799 square feet. Or, in other words, 0.21 square miles.