Okay kiddo, have you ever heard of a piggy bank? It's a place where you keep your money safe, right?
Well, a long time ago, the ancient Romans had something similar called the aerarium. It was like a giant piggy bank for the whole country!
Every year, the Romans would put some of their money into the aerarium. This money came from different sources – taxes, fines, and sometimes even from winning wars.
The aerarium was really important because it was used to pay for things that the government needed, like building roads and aqueducts, paying soldiers, and even helping the poor.
So, think of the aerarium as a big piggy bank that the whole country added money to, and then they used that money to make their city better for everyone.