The Orvieto Cathedral is a very big and pretty building in the city of Orvieto, which is in Italy. It is also sometimes called the Cathedral of Santa Maria Assunta.
Inside this big building, there are lots of beautiful things to look at. There are colorful paintings on the walls and ceilings, and lots of fancy sculptures made out of stone.
One of the most special things about the cathedral is that it has a big, round window that lets colorful light shine through it. People call this window a rose window, because it looks like a rose flower.
The cathedral is also very old, and it was built a long, long time ago. It took many, many years to build, because people wanted it to be perfect.
Lots of people visit the Orvieto Cathedral every year, because it is such a special and beautiful place. It reminds us of how talented people can create such amazing things, even a long time ago.