This paper presents the application of a minimalistic navigation strategy, based on the well-known BUG2 algorithm, to solve the problem of reaching a goal position in a multi-floor indoor scenario using a quadrotor. Examples of this scenario include buildings and in general cluttered indoor areas. As far as energy backup is concerned the quadrotor shows stricts constraints for this reason implementing a low-consumption navigation strategy is a major issue. We present a two-layer navigation strategy, called MF-BUG2, useful to navigate in multi-floor buildings starting from the ground floor toward the last or vice versa while searching for an interesting physical quantity (i.e,. gas leak, electromagnetic source). In the lower layer a BUG-like algorithm is able to drive the flying robot, equipped with a salient-cue sensor and a laser-range-finder, toward the estimated position of goal on the horizontal plane while avoiding …