Just my opinion but...
The 2 pictures were taken at different angles and distances on 2 different days. If you look at the second picture you'll see some discoloration of the monument stone. At a different angle it may look like a face. The monument looks like it might have been polished marble at one time. If you look at the side the face is sticking out of it seems like it is reflecting sky and trees. Also, because of the focus and angle, you may be catching part of a monument behind it or a reflection of a different monument.
Just because I tell you what I think it is, doesn't mean that what it really is. Just some possible explanations.
Anyway, it was still a good catch.