Check out the one-hour documentary “Building the Great Cathedrals,” which first aired on PBS’s NOVA in 2010, on YouTube. It goes a little “Dan Brown” on us with its supposed revelation of a Biblically based architectural code, but the writers and producers pay tribute to the tremendous ingenuity and effort that went into building these Gothic sacred places in the Middle Ages. The video is in the slightly-less-than-high-def 720p.