A series of three books which give a transcript of Richard Feynman's undergraduate Physics lectures at Cornell in the sixties. Still selling strong today, these books are a must for anyone keen on adding some sense of understanding to whatever dry or intractable Physics lectures they may have attended. Or indeed anyone else who wants to gain some insight into Feynman's genius.
The three volumes are:
  • Volume I: Sets the scene of classical physics, starting from how it relates to other sciences and why Physics in particular focuses on the more fundamental issues. The rest of the book is about classical dynamics and thermodynamics with optics thrown in too. Very good explanation of gyroscopic precession and an interesting aside on colour vision.
  • Volume II: Is mainly about electromagnetism, and covers the topic in great depth; it starts by introducing Maxwell's Equations in an intuitive manner and ends up discussing relativistic electrodynamics. Also has interesting chapters on fluid dynamics and curved spaces.
  • Volume III: Covers Quantum theory in a manner markedly different to any other textbook: he starts by introducing Dirac's formalism (considered quite advanced), and then looks at how this accounts for what we observe from the theory (where others usually start). It turns out to be a good idea, not only because it is a more modern approach, but also because it gives you a mental picture to deal with straight away (rather than starting in confusion and then trying to build one).

A brief reply to Suvrat's article: whether or not you would wish to read these books as an introduction to any given Physics course depends on how you choose to learn the subject. If you like to have everything ridgily defined, and presented in a way that follows a set syllabus, then reading the Feymann lectures first will probably be very confusing (indeed, quite a few of Feynmann's own students dropped out of his lectures due to confusion).
However, if understanding the underlying Physics is more important to you, then they are an ideal introduction. In fact, I found it helped to read the relevent sections before attending my own lectures made it a lot easier to follow what the lecturer was actually going on about. I think this was what I was trying to say above.