The "New Rose" Venn diagram with 11 curves linked at the end of the article is remarkably pretty and interesting: https://webhome.cs.uvic.ca/~ruskey/Publications/Venn11/Venn1...

That's neat. Venn Diagrams are one of these things you always take for granted but never stop to think how or why they work. They seem so "obvious" to us that it's easy to forget that someone must have invented them.