When hiking the Welland Canal Wetlands, a section of the 3rd Welland Canal containing locks 11 - 19, which can be viewed here, not only will you find the lock themselves, but I thought I would take the time to point out what else can be found in this area.

This seems to be the foundation for a lock keeper house or post. This is all that remains at this time though.You can find this next to Lock 11.
I found this a little ways outside of Lock 11, almost in the middle of Lock 11 and Lock 12 under the water, near the shore line. Not sure what exactly it could be. Unless it leads to the weir, which is in the picture below
Modernization at its finest. Located in between Locks 11 and 12 you will find a weir, which has been turned in to a water treatment facility.
All along the walk you will find numerous bollards located along the paths.
In between Locks 15 and 16 I spotted this in the woods. Apparently it is the base for a tower of some kind.
Just before Lock 17 you will see this CNR Railroad Swing Bridge. It is still in use today so please be careful! The gears are still there for rotating but it remains still today
Located on the other side of the canal and Seaway Haulage Road, you will find this tunnel. This is another tunnel people used to go underneath the CN Railroad to follow along old St.David's Road
In between Locks 17 and 18 you will find this weir in really good condition. Very solid and still to this day.
Roughly in the same area, but off in the forest are the trussels left from an old GTR bridge. These three columns stand proud, and are still in relatively good shape after all these years.