In recent years, the relationship between sculpture and architecture has become so close as to effect a merger, a situation more complex than it would initially appear. Richard Serra moves more and more inevitably into the realm of architectural space, giving his sculpture a massiveness of size that translates into work expressing the duration of time—an attribute that we often ascribe to architecture. And Frank Gehry has devoted much of his career to the creation of large sculptural spaces within the vocabulary of architecture. Part of the change in attitude has to do with technological ability: both Serra and Gehry rely on the computer to plan their often extraordinarily complex constructions. But there is also the recognition that contemporary art is most interesting when it embraces space that exists in between categories.