  Using the black hole merger rate inferred from LIGO, we calculate the
abundance of tightly bound binary black holes in the Milky Way galaxy. Binaries
with a small semimajor axis ($\lesssim 10 R_\odot$) originate at larger
separations through conventional formation mechanisms and evolve as a result of
gravitational wave emission. We find that LISA could detect them in the Milky
Way. We also identify possible X-ray signatures of such binaries.
