Okay kiddo, there's a really old wall in a place called Derbent that's really special because it was built a long, long time ago to protect a city. The wall is made of stone and stretches really far for many miles.
The people who built the wall were super smart because they made it really thick and tall, so nobody could break it easily. And they made it with little alcoves and towers so that soldiers could hide in them and shoot arrows at the bad guys.
The wall is so old and important that it was even named a UNESCO World Heritage Site, which means people from all over the world think it's really special and worth protecting.
So, the Derbent Wall is like a really, really giant and tough wall that kept bad guys away from a city a long time ago, and now people think it's really cool and important to keep it safe.