Intermediate-mass black holes, featuring masses of a few hundred to a few tens of thousands solar masses, have recently attracted quite some interest. They fill the gap between solar mass black holes and super-massive black holes and might be at the origin of the formation of the latter. After a decade of controversy, a few reliable intermediate-mass black holes are now known – they appear to lie on the black hole mass – sigma relation defined for super-massive black holes. Coincidence or physical cause? I will review the recent work of our group on intermediate-mass black holes at the centre of Galactic globular clusters and put them into the context of star cluster formation, nuclear clusters and super-massive black holes.