With the 11 February 2016 announcement by LIGO of the detection of GW150914, the era of gravitational wave astronomy has now passed a historical threshold. LIGO’s first gravitational wave event opens new avenues for astrophysical exploration and data analysis enhancements informed by direct detection. It should be recalled that the detectors that brought LIGO to success were first conceived almost a quarter century ago. Thus equally importantly, now is the time to start to plan how (and where) to build more sensitive third-generation detectors to probe the gravitational wave Universe to higher redshift.