Ubiquitous projection or "display everywhere" is a popular paradigm, according to which regular rooms are augmented with projected digital content in order to create immersive interactive environments. In this work, we revisit this concept, where instead of considering every physical surface and object as a display, we seek to determine areas that are suitable for the projection and interaction with digital information. After determining a set of requirements that such surfaces need to fulfil, we describe a novel computer vision-based technique to automatically detect rectangular surface regions that are deemed adequate for projection and mark those areas as available placeholders for users to use as "clean" displays. As a proof of concept, we show how content can be adaptively laid out in those placeholders using a simple tablet UI.