Abbey Detail

Our photography group has chosen the topic of "Churches and Cathedrals" this month, so I walked down to the Abbey this morning, camera in hand!
The most interesting pictures show some of the impressive detail, often overlooked perhaps. 
This is part of the main door. Was there another window here ? Why was this decorative pattern chosen? All sorts of questions come to mind!
The extra shows the front of the Abbey for anyone who would like to see it as a whole!