Aelia Capitolina was a city that was built a long, long time ago in a place called Jerusalem. It was built by people called Romans who took over the city. The Romans thought their own gods were very important, so they built a big temple to one of their gods in the city.
The people who lived in Jerusalem were already there and they had their own religion too. They didn't like that the Romans took over and built their own temple. They even made new rules that didn't make sense to the people who were already living there.
The Romans gave the city a new name, Aelia Capitolina, to make it seem like it was their own. They also made many changes to the city and the way it looked, so that it would be easier for them to control the people who lived there.
Aelia Capitolina was a very important city for a long time, but it changed hands many times over the years, and now it looks very different from how it looked back then. But people still talk about it and study it because it has a lot of history and is a fascinating place to learn about.