This is a really cool book written in 1884 (yes, 1884!) by Edwin A. Abbott. It's less than 100 pages and is a very interesting story about an entirely two-dimesional world (Flatland). The main character visits a one-dimensional world (Lineland) and then a three-dimensional world (Spaceland). If you think geometry is interesting at all you will like this.
You can read more about it at Amazon: Flatland book description.
The entire story is available online here: Flatland online text.
This is a really cool short story written in 1941 by Robert Heinlein about a house built in the shape of a tesseract (a four-dimensional 'cube') and what happens to it.
You can read more about it at Wikipedia: "...And He Built a Crooked House" story description.
The entire story is available here: "...And He Built a Crooked House" text.