Q is for What?

Q is for quoin.  I love, love, love old stone buildings!  The details in old stone architecture are just incredible.  See if you can identify a quoin in the montage below.  If you can identify all of the elements pictured, I might let you copy my homework next week!

Sources and key in follow up post.  This post is linked to Jenny Matlock's Alphabe-Thursday meme.