Martha and Allan were inspired by the symmetry and the layout of the Crystal Palace, and other Victorian greenhouse structures similar to it. While Martha's greenhouse is nowhere near the size of the Crystal Palace, it still occupies a nearly 3000 square-foot footprint - quite large for a residential greenhouse design.
Below are photographs of Martha's conservatory greenhouse. (She also has a vegetable greenhouse and a tropical hoop house!) Now that the weather in the Northeast has turned cold and the skies have become a perpetual grey, I thought it would be nice to show a little green. There is a video of Martha touring the greenhouse at the bottom of the post.