TITLE: Popular math books with depth
QUESTION [31 upvotes]: The most wonderful book I have ever read in my life was Fearless Symmetry by Avner Ash and Robert Gross, which is a good book that gives an intuition , and reasons behind the  introducing fields, need for Galois theory etc. 
I am interested in those books which possess the following characteristics ( as possessed by Fearless Symmetry :

A  good introduction to the concept, giving the reasons behind introducing theory X or some jargon Y in the arbitrary field chosen.
Requires a little mathematical background behind understanding that book, must be naive-user-friendly. 
And must be able to convey the things in a perfect manner.

Any mathematical area is fine with me
To frame in another manner, are there any Analogues of Fearless-Symmetry ? ( in other fields like Algebraic Geometry , Topology....etc)

REPLY [5 votes]: Maybe Geometry and the Imagination by David Hilbert and Stefan Cohn-Vossen.