Xishiku Cathedral is a big and pretty church in China, kind of like the ones you see in movies. It's also called Beitang or North Cathedral, because it's in the north part of Beijing, which is a big city in China.
The church is very old, it was built over a hundred years ago, before most of us were even born! It was made by some people from France, who wanted to spread Christianity (that's a religion, like what you might learn about in your Sunday school or at home).
Xishiku Cathedral has a tall spire with a bell, that makes a ringing sound when it's time for church service. It also has beautiful stained-glass windows, which are colorful and shine in the sunlight. People who go to the church get to pray and sing songs, and sometimes there are special celebrations for holidays like Christmas.
Overall, Xishiku Cathedral is a special and important place for people who believe in Christianity and want to worship together.