Black Holes in Galactic Nuclei: the Promise and the Facts
  It has long been suspected that Active Galactic Nuclei are powered by accretion of matter onto massive black holes and this belief implies their presence in the nuclei of most nearby galaxies as "relics" of past activity. Just a few years ago this was considered a paradigm but, recently, new ground-based and Hubble Space Telescope observations are producing a breakthrough in our knowledge on massive black holes. I will review the evidence for the existence of black holes in galactic nuclei and how their presence is related to host galaxy properties and AGN activity. 
Alessandro Marconi (Arcetri Observatory)