The activity at the galactic center might be fuelled by energy release near a large black hole. In this talk I describe some relativistic effects which may be relevant to this process. I use Newtonian language so far as possible and illustrate the effects with simple  analogies. Specifically, I describe the gravitational field near a black hole, Lensâ€Thirring and geodetic precession, electroâ€magnetic energy extraction of the spin energy of a black hole and the structure of accretion tori around black holes. ; © 1982 AIP Publishing. Supported in part by the National Science Foundation [AST79-22012]. This paper is identical to "Black Holes and the Origin of Radio Sources", Kip S. Thorne and Roger D. Blandford, in "Extragalactic Radio Sources", Proceedings IAU Symposium #97, ed. D. S. Heeschen and C. M. Wade (Reidel, Dordrecht, Holland 1981). ; Published - 1_2E33481.pdf