Thought House I
In the short film we watched in the visitor's center as an introduction to our tour, there was a moment where the Jefferson re-enactor was seen to walk into this little pavilion for reflection during a time of crisis. It seemed to be the thing that people remembered most easily, and everyone exclaimed "There it is!" when they came across it on the south side of the estate, near the kitchen gardens.
It's a tiny room with great views. Because of its portrayal in the film we called it the "Thought House".