I am currently reading three:
Modern and Modernism-The Sovereignty of the Artist 1885-1925-by Frederick Karl. While focused mainly on literature, this explores the growth of Modernism and Avant Garde movements. Equal parts literary and cultural criticism.
Jean-Christophe-by Romain Rolland-The story, both internal and external, of a musician who led an idyllic childhood (for an artist anyway), being beaten daily by an alcoholic father. He runs off to Paris to meet his (you fill in the blank).
Course in General Linguistics-Ferdinand de Saussure-Along with Pierce, this is one of the building blocks in the foundation of semiotics. A bit thick in places, but if you are interested in language (which everyone should be since language is now reality) it is well worth the read.

A few others you should check out-
Sleepwalkers-Hermann Broch
Mysteries-Knut Hamsun
If on a Winter's Night a Traveler-Italo Calvino-Quite simply, one of the best books ever written.
For you mathematicians and physicists out there, Flatland by Edwinn Abbot

Always remember, reading will take you further afield than any other endeavor, yet it is a dying art. Do the world a favor and turn someone on to reading.