I like books that go deep into a topic in an encyclopedic but are not terse (ie. they are not full fledged textbooks).
Some of the books of this sort I liked are :
- Quantum by Manjit Kumar
- Anatomy of Melancholy
- Prime Obsession : Bernard Riemann
- Mossad: Greatest Missions
- Le Tom Beau De Marhot by Hofstader
- Chaos: Making of a New Science
- The Road to Reality by Roger Penrose
- The Gulag Archipelago
- Musicophilia by Oliver Sacks
- Crussades by Thomas Asbridge
by CollarOk3912