The detection of GW150914 is a landmark in the history of astronomy, 
not only because it is the first gravitational wave (GW) detection, 
but also because it reveals a very active universe possibly rich of 
black hole binaries (BHBs) beyond expectations. I will talk shortly 
about the detection and properties of GW150914 and then highlight 
implications of this event for future multi-band GW astronomy. 
One of the most exciting prospects is the prior localization of BHB mergers: 
a space-based detector like eLISA will tell aLIGO and all electromagnetic 
instruments when and where a BHB coalescence will occur with several week 
notice. This will make coincident multimessenger observation of BHBs a reality.