A fortress church (German: Kirchenburg) is a particular type of church that, in addition to its religious functions is also used by the local population as a retreat and defensive position, similar to a refuge castle. A fortress church usually implies that the church is enclosed by its own fortifications, such as curtain walls and defensive towers. By comparison, a church with simple defensive features, such as battlements and embrasures on the church itself, is usually just referred to as a fortified church.