If you have ever seen a soccer game or a concert on a large screen TV; then you have been surely impressed with the captivating and amazing display. This is not limited to entertainment alone â€” the effect also is the same in more serious applications. In this respect; size matters. In most cases we cannot simply use the algorithms for standard displays on large screensâ€”the size of the display significantly affects most visualizations and interaction modalities. Therefore; we need to understand the advantages and disadvantages of this medium; and the ways large screens are different or similar to smaller screens. Beside the need to develop special hardware and software; we always have to think about the user of such environments. Does he or she really need a wall-sized screen? Can he or she really make use of a gigapixel display wall? In the keynote we will give an overview of HCI and Visualization techniques dealing with large display environments. We will discuss how much size users really need and think about alternative approaches.