FLATLAND...Encounters of the Third Kind (Websites)
And continuing the discussion of my old favorite FLATLAND: A Romance of Many Dimensions (1884) by Edwin Abbott....
Tons of materials are a "link" away on the Internet, including animations (such as Nick Mee's 4D cube animation as shown). Though I will list some web sites that are helpful and insightful, do not blame me when noticeing that you have just lost 4-5 hours of your life...plus be forewarned that some sites are somewhat strange:
Hope you find these sites fun, interesting, and helpful....if you know of others that should appear on this list, please send them to me.