<P> The Ruthwell Cross, a stone Anglo - Saxon cross located in Ruthwell, Dumfriesshire </P> <Li> <P> The World Trade Center Cross rises from the World Trade Center wreckage . </P> </Li> <P> The World Trade Center Cross rises from the World Trade Center wreckage . </P> <Li> <P> The Cross in Melaten - Friedhof, Köln, Germany </P> </Li>

When did the cross became a christian symbol