The Adams Synchronological Chart or Map of History is like a very big timeline that shows all the important stuff that has happened in the world from the beginning of time until now. It's kind of like a big history book, but instead of reading it, you look at pictures and dates and see how everything fits together.
Imagine you have a really big piece of paper that's taller than you and wider than your room. On that paper, you draw a line at the bottom, and that line is the beginning of time, like when the Earth was first made. Then you draw another line higher up, and that's when the first humans appeared on the Earth. Then you keep drawing lines and adding more events as you go along.
The Adams Synchronological Chart has pictures and short descriptions of all the important things that happened in different parts of the world, like when the pyramids in Egypt were built or when Christopher Columbus sailed across the ocean. The chart shows how everything is connected and how different cultures and civilizations influenced each other.
It's like a really big puzzle that shows how history is all connected, and it helps you understand how the world we live in today was shaped by what happened in the past.