Spatial map of observed stars. The lower right region is empty because of our sample selection choice. Symbols as in Fig. 5, with the addition of big circles to indicate B stars (blue), late-B to early-A stars (cyan), candidate B supergiants (black), and probable (orange) or possible (violet) O stars. We also plot O stars from Walborn (1973) as black crosses. The most massive of these stars (surrounded by big black circles) are taken as centers of the respective subregions, bounded by red dashed lines, and labeled in red after the central star names (except for Trumpler 14, whose central star is HD 93129A). Dashed black segments delimit the dark V-shaped dust lanes in front of the nebula. The solid gray circle to the NW of η Car indicates approximate location and size of the Keyhole nebula (Smith & Brooks 2008).