  A number of neutron stars have been observed within the remnants of the
core-collapse supernova explosions that created them. In contrast, black holes
are not yet clearly associated with supernova remnants. Indeed, some
observations suggest that black holes are ``born in the dark'', i.e. without a
supernova explosion. Herein, we present a multi-wavelength analysis of the
X-ray transient Swift J1728.9$-$3613, based on observations made with Chandra,
ESO-VISTA, MeerKAT, NICER, NuSTAR, Swift, and XMM-Newton. Three independent
diagnostics indicate that the system likely harbors a black hole primary.
Infrared imaging signals a massive companion star that is broadly consistent
with an A or B spectral type. Most importantly, the X-ray binary lies within
the central region of the catalogued supernova remnant G351.9$-$0.9. Our deep
MeerKAT image at 1.28~GHz signals that the remnant is in the Sedov phase; this
fact and the non-detection of the soft X-ray emission expected from such a
remnant argue that it lies at a distance that could coincide with the black
hole. Utilizing a formal measurement of the distance to Swift J1728.9$-$3613
($d = 8.4\pm 0.8$ kpc), a lower limit on the distance to G351.9$-$0.9 ($d \geq
7.5$ kpc), and the number and distribution of black holes and supernova
remnants within the Milky Way, extensive simulations suggest that the
probability of a chance superposition is $<1.7\%$ ($99.7\%$ credible interval).
The discovery of a black hole within a supernova remnant would support
numerical simulations that produce black holes and remnants, and thus provide
clear observational evidence of distinct black hole formation channels. We
discuss the robustness of our analysis and some challenges to this
interpretation.
