Johnson calls the building Monster. Made of concrete sprayed on to a flexible metal framework, it is a random agglomeration of oddly shaped solids - curved, slanted, spiky, bulbous. The door is approximately trapezoidal; within, the spatial anarchy of the exterior is faithfully repeated.
Monster is a gleeful negation of everything Johnson's first and most famous building on this site represented: opacity versus transparency; computer-generated anarchy versus Euclidean simplicity; the colours of death and violence versus the absence of colour. With the Glass House you could discover nearly everything there was to know about it while standing outside. Monster makes no conventional sense, even when you are standing in the middle of it.
Johnson has always been a jester, and it is in character that this building, so different from everything else he has ever built, should be intended as the visitor centre for the estate when it is taken over by the National Trust for Historic Preservation on Johnson's death. It is an orientation centre that will itself be disorientating, both physically and intellectually. But like many of Johnson's jokes, this has a serious point. The buildings on the estate describe Johnson's journey from the rigorous Modernism of his youth through various tentative alternatives, to something radically new. It is the story of the slow erosion of Modernist certainties; and Monster, which shows the influence of his friends Peter Eisenman and Frank Gehry, is a suitable place for the journey to end. It is an attempt to discover new principles of design - principles which reflect physicists' visions of the universe's chaos and complexity, and the ability of computers to realise such visions.
Philip Johnson has been America's most famous architect for as long as anyone can remember, yet even his admirers hesitate to call him truly great. Throughout his career he has been an opportunist and a magpie rather than a figure of real originality. The Glass House was resoundingly inspired by Mies van der Rohe, who later paid Johnson the compliment of bringing him in as partner on the Seagram Building, Mies's skyscraper on Park Avenue. In time, Johnson rejected the stark perpendicularity of Mies, and fell prey instead to a succession of stylistic tricks and fads: the sub-classical facade and columns of the Sheldon Memorial Art Gallery, the parabolic dome of the Roofless Church in Indiana, and the Corbusian brutalism of the nuclear reactor at Rehovot in Israel. At the time such reckless eclecticism infuriated the orthodox Modernists, especially in Britain, but now that Modernism itself is so deeply out of fashion, Johnson's whimsicality seems somehow less venal.
His most famous building is probably the AT&T Tower (now the Sony Building) in Manhattan, with the broken pediment of its roofline reminiscent of the top of a Chippendale highboy. Built in 1984, the AT&T Tower woke the non-architectural world up to the notion of Post-Modernism, and at a stroke made all the flat-topped skyscrapers of the city look dull and passe. But it was an achievement of mind-numbing superficiality, suggesting that all the modern American architect could hope to do was tinker with style - and that Johnson, for one, was happy with such a trivial role. To ram home the point, he followed it with a succession of terrible Po-Mo corporate HQs in other American cities, including the Pittsburgh Plate Glass building - Westminster Abbey shot several hundred feet up in the air and vitrified - and the pseudo-Gothic NCNB Center in Houston.
Monster may do something to redeem the damage done to Johnson's reputation by these works. It is an old man's folly - but set in an estate full of follies, for Johnson's inherited wealth meant he was always able to indulge his whims. Besides the Glass House, visitors will find the brick oblong of the Guest House, a painting gallery buried in turf, an under-size pavilion on a lake which can only be reached by taking a leap from the shore, and a 36ft-high tower of eccentrically arranged concrete blocks which is easy to climb but fiendishly hard to descend from. Monster, despite its stylistic remove from these works, makes a suitable entrance gate to Philip Johnson's polymorphously perverse world. !Reuse content