A pointed cone shape on top of a building is called a spire, especially when it rises from the roof of a church.
The part of a church roof that rises above a city skyline or a village's rolling hills, pointing sharply up toward the sky, is its spire. Many church spires have a cross at the very top. Other buildings — religious or secular — can also have spires, though it's most common to see one on a Christian church. The root of spire is the Old English spir, "sprout, shoot, or stalk of grass."