The era of modern cylindrical screens, so-called advertising columns, began in the middle of the 19th century. Even nowadays they are still a popular advertising medium, which integrates well with urban environments. With advances in display technologies (LEDs, projectors) digital forms of such columns emerge and enable novel forms of visualization and interaction, which significantly differ from flat, rectangular screens due to the round shape. In this paper we present the design space for large cylindrical screens and outline design principles based on observations and experiments with a prototype of a digital column. We especially focus on the differences with flat, rectangular displays and report on challenges related to the deployment and development of applications for cylindrical screens.