Has the universe always existed or was it created from nothing? Is it finite or infinite in extent? If it is finite, does it have an edge? Does it then make sense to talk of spaces beyond the edge? Until the 1920's, scientists by and large left this kind of questions to religion and philosophy. Then Hubble found that the universe is expanding, as predicted by Einstein's theory of General Relativity. Now we have plenty of evidence that, as far in the sky as our instruments can see, it all started about 15 billions years ago with a Big Bang. We will trace the history of the great discoveries that have led to this conclusion, following in part Hawking's book "A Brief History of Time". We will see how our notions of space and time, and of the ultimate structure of matter, have evolved into a theory wilder than imagination, in which matter and antimatter are created from pure energy and an entire galaxy can disappear into a black hole. Yet this theory explains in detail what happened within seconds after the Big Bang. Thus some of the ancient dilemmas have been resolved, but the end of the story is nowhere in sight. Did the Big Bang really originate everything, or was there something before? Is this the only possible universe, or the best of all possible universes, or did it turn out this way by chance? We will find out, from taped interviews and non-technical articles, how leading cosmologists try to answer these basic questions.