The Math Book by Clifford A. Pickover
Mathematical inventions and discoveries presented through a historical lense. From the archaic "Ant Odometer" over 150 million years ago, to the "Mathematical Universe Hypothesis" in 2007, this book covers many of Math's triumphs.
Infinite Powers by Steven Strogatz
Calculus newcomers and experts alike will appreciate this book. Professor Strogatz lays out the foundations of Calculus and connects this to the world we inhabit. He makes the case that understanding Calculus allows us to shine a light on the darkest parts of the universe.
Flatland by Edwin A. Abbott
An interesting take on society and its structure, imagining our own heirachries as dimensions of Mathematical spaces. A great read to ponder and ask yourself where you may reside in Flatland.