Energy-coded three-colour image built from our six XMM-Newton observations of Cyg OB2. The red, green, and blue colours correspond to the soft, medium, and hard energy bands used throughout this paper (see text). The individual EPIC images were exposure corrected, the stray-light features from Cyg X-3 (lower right corner) were excluded, and the out-of-time events from the bright central source (Cyg OB2 #8a) were removed before the images were combined. A preliminary version of this figure was published by Rauw et al. (2008).