This paper will present the argument that while Problem Based Learning (PBL) (or its variant Project Based Learning, PjBL) provides significant benefits and advantages to student learning in of itself, the full benefit of PBL is only completely realised as part of an "integrated" curriculum that provides a variety of learning opportunities and instructional support. We propose that PBL should be more widely considered and used as the key integrative feature within a curriculum to enable programmes to connect theory, practice, societal context, values and skills as well as to break the mentality that comes with modularisation. To do this, we suggest that a coherent thread of PBL should be enacted that is stratified to progress students through increasingly open problems and projects, each connected to other aspects of the taught curriculum while enabling skills development and the formation of professional and responsible attitudes and attributes. We provide some examples from our own experience in Engineering but advocate that this approach is much more widely applicable within higher education.