Invention by deisgn: How Engineers Get from Thought to Thing by Henry Petroski was one of my latest engineering related reads.
The book starts off with the design of the paper clip. The show patents and improvements on this basic design. The book progresses through skyscrappers and bridges. The book is easy to read and entertaining. plus, it is informational. The book also works well as a combination read with Mario Salvadori's Why Building Stand Up and Why Buildings Fall Down.