Complex adaptive systems can be characterised by many adaptively changing parts, with a large number of interactions, and adaptation at the system level. This body of research can inform the large engineering projects that are characterised by large systems of systems, where interactions to achieve end goals matters, and where designs and the technology of parts in service undergo many adaptive changes. A number of key lessons can be drawn from the complex adaptive systems literature. Firstly, that the use of design patterns, as traditionally applied in software engineering, can also be applied to wider systems engineering and systems integration issues; in particular, the use of the "bow-tie" architectural pattern drives compatibility between different pieces of kit that can then evolve independently. Another key lesson is that focussing on the adaptive learning processes in individuals and groups fosters positive decision-making about complex integration problems.