The most consistent design error over three centuries has been designing the entire office for one type of activity at the expense of the other. Open-plan designs optimised for collaboration consistently created environments hostile to focused individual work. Closed, segmented designs optimised for privacy consistently limited the spontaneous social interaction that builds culture and creative energy. The lesson: a high-performance office must provide both, with the ability to transition between acoustic environments based on the task at hand — not commit the entire floor to one acoustic condition.