Constructed in the early 1980s, the Lloyd’s Building in London is one of the most significant architectural projects of the late modern era. Based on a design by Richard Rogers + Partners, it transformed concepts of the megastructure and the intelligent environment into built reality. Mock-ups, or full-size models, played a crucial role in the building’s design process, as they enabled the testing and refinement of novel constructions, thereby minimising the risks of this ambitious project. From the archives of Rogers Stirk Harbour + Partners, Josef Gartner, and Arup, this book reconstructs the working methods to show how mock-ups were used as research and planning tools.