  Discovery of strongly-lensed gravitational wave (GW) sources will unveil
binary compact objects at higher redshifts and lower intrinsic luminosities
than is possible without lensing. Such systems will yield unprecedented
constraints on the mass distribution in galaxy clusters, measurements of the
polarization of GWs, tests of General Relativity, and constraints on the Hubble
parameter. Excited by these prospects, and intrigued by the presence of
so-called "heavy black holes" in the early detections by LIGO-Virgo, we
commenced a search for strongly-lensed GWs and possible electromagnetic
counterparts in the latter stages of the second LIGO observing run (O2). Here,
we summarise our calculation of the detection rate of strongly-lensed GWs,
describe our review of BBH detections from O1, outline our observing strategy
in O2, summarize our follow-up observations of GW170814, and discuss the future
prospects of detection.
