You don't need to be religious to enjoy the serene atmosphere of Astorga Cathedral. Check when the next mass is scheduled or when it's open for general viewing.
This principal church in Astorga is well-liked by many travelers, so make sure it features on your to-do list. Don't think that's all there is to do here, though. There are plenty more places waiting for you to experience after Astorga Cathedral. Museo del Chocolate, City Hall, and Episcopal Palace are close by.