A Latin cross or crux immissa is a type of cross in which the vertical beam sticks above the crossbeam,[1] 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.[2]
If displayed upside down it is called St. Peter's Cross, because he was executed on this type of cross.[3] When displayed sideways it is called St. Philip's cross for the same reason.[3]
Many medieval churches 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.