Maher Cross detail 

Here's a closer shot of the cross. In the four corners you'll see a bull, lion, angel, eagle. These can represent the four apostles or beasts of the apocalypse. They also have astrological meanings. Bull/Taurus, Lion/Leo, Angel/Aquarius, Eagle/Scorpio and Cardinal themes along Earth/Air/Fire/Water lines.

These four symbols are seen in many cathedrals across Europe above the main portal.