Marker tracking has revolutionized Augmented Reality about a decade ago. However, this revolution came at the expense of visual clutter. In this paper, we propose several new marker techniques, which are less obtrusive than the usual black and white squares. Furthermore, we report methods that allow tracking beyond the visibility of these markers further improving robustness. All presented techniques are implemented in a single tracking library, are highly efficient in their memory and CPU usage and run at interactive frame rates on mobile phones.