The house was designed in 1920 by John Russell Pope for Irwin Laughlin (of Pittsburgh!). The house is immediately next door to another of his spectacular houses, the Henry White residence from 1912, which currently forms a campus with the Laughlin house for the Meridian Foundation. More on the Henry White house at a later date.
Michael Hampton demonstrates how it works above, haha. What door?!
As I mentioned the gallery is the spine of the ground floor. Above one sees through the gallery from the drawing room into the dining room beyond. I know a lot of architects say lining up vistas 'doesn't matter' but when it's done right YOU NOTICE. It does matter: symmetry and enfilades, sign me up!
The stair is lit by a laylight and skylight above.