  We propose a new formation channel for intermediate mass black hole (IMBH)
binaries via globular cluster collisions in the Galactic disc. Using numerical
simulations, we show that the IMBHs form a tight binary that enters the
gravitational waves (GWs) emission dominated regime driven by stellar
interactions, and ultimately merge in $\lesssim 0.5$ Gyr. These events are
clearly audible to LISA and can be associated with electromagnetic emission
during the last evolutionary stages. During their orbital evolution, the IMBHs
produce runaway stars comparable with GAIA and LAMOST observations.
