A 'known unknown' structure

The footpath through Ellastone & Calwich takes one past this stone structure standing at the end of a bridge.  It might be historic, as it was probably on the estate of Calwich Abbey Hall (two hundred yards away), which has a long history anyway.
Was it a small gatehouse?

However, it seems to serve no purpose now.
What I like about that is that the estate's owners have just left it alone.  Or maybe they couldn't be bothered to do anything other, than leave it alone....

Knot in a twist

This rather handsome iron girder holds up the roof of the Cheadle Indoor Market - the manufacturer is Silvester & Hopkins, a firm which specialised in iron winding machinery for the area's coal-mines.

As a nod to the locality, S&H placed a Stafford Knot in their maker's mark.
Trouble is: they have the knot upside down.   (Yes, I know: only I would care about this!!)

Lift a bridge over a canal

Sometimes called a liftbridge, but what I know as a drawbridge, this structure sits on Caldon Canal near Stockton Brook. It enables people from the farm (on the other side to the path) to move their cattle across the canal - while also letting narrowboats through.

I suppose they must be common enough, as it's a straightforward enough piece of mechanics, but I've not seen many.