As Intelligent Environments research continues in its various guises, there is an increase in the scale at which investigation is being conducted. Projects are looking beyond single-room and apartment sized living-labs that have provided us with initial testbeds for early research and are envisioning grander designs on the scale of entire buildings, campus or towns. But now we must ask if the knowledge we have gained previously can scale upwards, or are new methods and models required to break free from the confines of controlled labs and into real-world deployments where multi-user is the norm not the exception. In the discourse of this paper, we describe what Large-Scale Intelligent Environments (LSIEs) are and identify some of the challenges that relate to realizing them. We highlight the importance of security, standards and infrastructure so that human users can roam confidently from place-to-place whilst enjoying a seamless continuity of experience.