  Supermassive black holes have generally been recognized as the most
destructive force in nature. But in recent years, they have undergone a
dramatic shift in paradigm. These objects may have been critical to the
formation of structure in the early universe, spawning bursts of star formation
and nucleating proto-galactic condensations. Possibly half of all the radiation
produced after the Big Bang may be attributed to them, whose number is now
known to exceed 300 million. The most accessible among them is situated at the
Center of Our Galaxy. In the following pages, we will examine the evidence that
has brought us to this point, and we will understand why many expect to
actually image the event horizon of the Galaxy's central black hole within this
decade.
