Imagine a really, really big fort with tall walls that go all the way around it. That's kind of what the Walled City of Lahore is like! It's a place in Pakistan where people have lived for a really long time, and it's just called the "walled city" because it's surrounded by those big walls.
Inside the walls, there are lots of little streets and buildings that go way back in time. Some of them are really old, and have been there for hundreds of years! They're made of bricks and stones, and some of them have really fancy designs on them, too.
People still live and work inside the walled city, too. And because it's been around for so long, there are lots of different cultures and religions that have all mixed together. So you might see a mosque (where Muslims go to pray) across the street from a temple (where Hindus go to pray), for example.
There are also lots of markets and shops inside the walled city, so you can buy all kinds of things there - like jewelry, clothes, and even food! And sometimes, during special festivals or holidays, the whole walled city will light up with decorations and music. It's really cool to see!