I have been interested in castles and fortifications since I was a teenager playing Dungeons and Dragons.  Part of my fascination has been with the architecture and building techniques used to construct the great castles of the Middle Ages.  In college I read about medieval and gothic styles of  architecture and learned as much as I could.  Since then, I have made several trips to Europe and have had the opportunity to examine the various architectural styles first hand.  Surprisingly, my favorite structures have been churches and not castles because churches tend to have more elaborate features (buttresses, columns, high vaulted ceilings, etc.) and more ornate stonework . They are both functional and beautiful.
Interior of St. Eustache in Paris Westminster Abbey in London
Notre Dame in Paris
The Forum Des Halles in Paris
The columns of Jedburgh Abbey.
An ornate archway at Jedburgh Abbey in southern Scotland