This is a visualization of my MacBook Air's keyboard. It has 127 symbols spread across 78 keys. I found an approximate date for every symbol. Most of these symbols are thousands of years old. Play around or read more here.
You can click each symbol to see the source where I pulled an approximate year. Pull requests are accepted as some may be off by hundreds of years, but the theme should hold.
The keyboard shown isn't quite my MacBook Air's keyboard but adapted from this Apple Keyboard in CSS
The Table of mathematical symbols by introduction date was very helpful.