Latin cross

A Latin cross or crux immissa is a type of Christian cross in which the vertical beam sticks above the crossbeam, giving the cross four arms. Typically the two horizontal and upper vertical arm are the same length, although sometimes the vertical is shorter, however the lower vertical arm is always much longer than any other arm.

When displayed upside down it is called St. Peter's Cross, because according to Catholic tradition he was executed on a cross of this type. When displayed sideways, it is called St. Philip's cross for an analogous reason.

Many churches of different time periods are designed using the Latin cross plan. When looked at from above, it takes the shape of a Latin cross. A Latin cross plan primarily contains a nave, transept, apse, and narthex.