A church, church building or church house is a building used for Christian worship services and other Christian religious activities. The earliest identified Christian church is a house church founded between 233 and 256. From the 11th through the 14th centuries, there was a wave of church construction in Western Europe.

Sometimes, the word church is used by analogy for the buildings of other religions. Church is also used to describe the Christian religious community as a whole, or a body or an assembly of Christian believers around the world.

In traditional Christian architecture, the plan view of a church often forms a Christian cross; the center aisle and seating representing the vertical beam with the bema and altar forming the horizontal. Towers or domes may inspire contemplation of the heavens. Modern churches have a variety of architectural styles and layouts. Some buildings designed for other purposes have been converted to churches, while many original church buildings have been put to other uses.