There’s a moment five minutes into Charlie Rose’s 2003 interview with Louis Kahn’s son in which he’s asked to define his father’s “greatness.” Nathaniel Kahn seems uncomfortable with the question, responding with the caveat, “I’m not an architectural historian.” This would not seem odd but for the fact that Kahn had just directed, written, and produced an Oscar-nominated documentary about his father. Surely, he is a historian of some kind.

In the past 15 years, a subgenre of architectural documen…