Tycho Brahe's observations of a supernova in 1572 challenged the dogma that the celestial realm was unchanging. Now, 440 years later we have once again seen the light that Tycho saw as simple reflections from walls of Galactic dust. These light echoes, as well as ones detected from other historical events such as Cas A and Eta Carinae's Great Eruption, give us a rare opportunity in astronomy: the direct observation of the cause (the explosion/eruption) and the effect (the remnant) of the same astronomical event. But we can do more: the light echoes let us look at the explosion from different angles, and permit us to map the asymmetries in the explosion. I will discuss how the unprecedented three-dimensional view of these exciting events allows us to unravel some of their secrets.