Johnson's early influence as a practicing architect was his use of glass. The Glass House (1949) that he designed as his own residence in New Canaan, Connecticut was a profoundly influential work, but "universally viewed as having been derived from" the Farnsworth House, according to Alice T. Friedman. Johnson curated an exhibit of Mies van der Rohe work at the Museum of Modern Art in 1947, featuring a model of the glass Farnsworth House.
The concept of a Glass House set in a landscape with views as its real "walls" had been developed by many authors in the German Glasarchitektur drawings of the 1920s, and already realized by Johnson's mentor Mies. The building is an essay in minimal structure, geometry, proportion, and the effects of transparency and reflection.
The house sits at the edge of a crest on Johnson's estate overlooking a pond. The building's sides are glass and charcoal-painted steel; the floor, of brick, is not flush with the ground but sits 10 inches above. The interior is an open space divided by low walnut cabinets; a brick cylinder contains the bathroom and is the only object to reach floor to ceiling.
Johnson continued to build structures on his estate as architectural essays. Offset obliquely fifty feet from the Glass House is a guest house, echoing the proportions of the Glass House and completely enclosed in brick (except for three large circular windows at the rear, set in wooden frames, 5 feet in diameter, which reveal the interior of the building that was originally designed with a window in each of three rooms, two guest bedrooms at each end and a study in the middle). It now contains a bathroom, library, and single bedroom with a vaulted ceiling and shag carpet. It was built at the same time as the Glass House and can be seen as its formal counterpart. Johnson stated that he deliberately designed it to be less than perfectly comfortable, as "guests are like fish, they should only last three days at most".
Later, Johnson added a painting gallery with an innovative viewing mechanism of rotating walls to hold paintings (influenced by the Hogarth displays at Sir John Soane's house), followed by a sky-lit sculpture gallery. The last structures Johnson built on the estate were a library and a reception building, the latter, red and black in color and of curving walls. Johnson viewed the ensemble of one-room buildings as a total work of art, claiming that it was his best and only "landscape project."
The Philip Johnson Glass House is a site of the National Trust for Historic Preservation and now open to the public for tours.