[auntienomen]

Feynman's PhD advisor, John Wheeler, together with Charles Misner and Kip Thorns, wrote a textbook on general relativity called Gravitation. It's gigantic, 1200 pages, and its tone is similar to the Feynman lectures. And it is at least partially a math textbook, as it includes a fairly complete introduction to Riemannian geometry.

[tobinfricke]

I think even among professionals in general relativity, MTW has developed a reputation as being too dense and old-fashioned, certainly so for a beginner. If you're first approaching GR, Sean Carroll's notes or books are much more approachable.

[auntienomen]

True, but the question was about books that are like the Feynman Lectures. MTW has similar tone and breadth, and a similar reputation for being useless for learning.

For actually learning GR, I prefer Wald.