Terrestrial Gravitational-Wave Detector Arrays in the 21st Century*

The early observation runs of the two Advanced LIGO interferometers mark the beginning of gravitational-wave astronomy. The extend to which this new branch of astronomy can bloom depends soley on the quality and number of available detectors. I will outline the plans of LIGO and its partners VIRGO and KAGRA for achieving design sensitivity and upgrading the detectors. Furthermore I will explore the options for future gravitational-wave detector arrays, a generarion of detectors that can provide the backbone infrastructure for gravitational-wave astronomy for the rest of the 21st century.