The fabric of the cosmos
The second half of the book gets on to symmetry, particle physics, and of course string theory. Greene shows how the field of quantum cosmology has arisen, looking at the earliest moments after the big bang, as well as leading to more speculative ideas such as a universe on a brane.
Although this book is non-technical, it is intellectually deep, and is likely to have something of interest even for those experienced in the subject - there are plenty of notes at the end for those wanting more details. Greene manages to include a great deal of modern physics without resorting to equations, and I would recommend this book to anyone wanting to know about current ideas regarding the universe in which we live