Fort Hood, TX -- The largest movie set in America has been built on the largest active-duty Army base in the country, deep in the heart of Texas. U.S. Army personnel vet visitors before they arrive in what appears to be a Middle Eastern city. The 113 buildings, many of them bullet-pocked, line narrow streets where burned husks of Humvees are reminders of a terrible day. This is such a convincing replica of Sadr City, Iraq, that veterans who fought there walk around the set visibly shaken. It’s that sort of dedication to accuracy upon which National Geographic has built its reputation. The Long Road Home only adds to that luster. The eight-episode scripted series premiering tomorrow night (Nov. 7) is based on the 2007 bestseller by ABC’s chief global affairs correspondent Martha Raddatz -- and it is one of the most powerful and important programs of the year.