Current "inflationary" theory has the universe expanding at a colossal increasing rate in its first moments, so that tiny subatomic-particle-sized irregularities got expanded up to a kind of space-foam made of galaxies that we see in our telescopes today. Following this theory, what can be observed today is only a very very small part of the actual universe most of which is receding from us so fast that light from it will never reach us and so will never be observeable. We can only speculate as to what is outside our local observeable universe - we can't even tell if it has the same physics we do - let alone what might be at any "edge" of the actual universe. Having said that, the simplest solutions to Einstein's equations for the universe leave the universe finite and unbounded. Using this theory, just as the surface of a sphere has no end, but it has finite area, so the universe has no end, but has a finite volume. If you stopped the universe expanding and went for a walk along a beam of light, you would eventually end up at your starting point just as you would taking a walk on the surface of a sphere. But while a sphere has an outside, the equations don't leave room for an "outside" of the universe - the universe is all there is. In newer theories, such as M-Theory, there are huge numbers of possibilities for what's "outside" and hopefully new experiments will be able to shed some more light.

everything ends somewhere, and where something ends something else begins.

I think that the universe is like a circle because the universe is warped...so you would end up where you started if u made it to the edge...but since its always expanding its realistically imposible to find out....:(