Cologne Cathedral is a very big building with a lot of history! It's in a city called Cologne in Germany. The building is super tall and has lots of big windows made out of colorful glass. The people who built it a long time ago wanted it to be very special, so they spent a long time making it just right.
It's a very old building, over 700 years old, which means it's been around for a super long time! Lots of people go to visit it every day to see all the pretty things inside like the enormous organ, beautiful paintings and gold sculptures.
The cathedral is also really important because it's part of a religion called Christianity which means many people go there to worship and pray. But even if you don't follow this religion, people still love to visit the cathedral because it's just so cool to see such a big and beautiful building with so much history!