The original Campbell House was built in 1952. The Goldberg House is actually just a relatively modest expansion of that original house and is not a complete replacement. It is worth noting that interior and exterior walls and design were almost completely replaced while the Goldberg family were living in the house.
Featured in "The Harvard Five in New Canaan" by William D. Earls, AIA: http://www.amazon.com/Harvard-Five-New-Canaan-Midcentury/dp/0393731839/ref=sr_1_1?s=books&ie=UTF8&qid=1325264175&sr=1-1.