On this 20th anniversary of 9/11, I bring to you yet again one of the best documentaries covering the collapse of the Twin towers and the 40 story tall sky scraper known as Building 7 (aka The Salomon Brothers building).

If you’ve never seen this, prepare to have your head explode. I met Richard at a conference several years ago. He’s one of the nicest and most intelligent people I’ve ever met in my life.