That's interesting. As this place was undergoing a lot of work I wonder if these are old or retro??? Actually, they looked pretty old. Did you notice the wires at the tops? They hold things in place to stop birds nesting on/in the chimneys.
I don't have that look down angle to tell, but I'm sure they have some type of screen to keep critters out. I've seen a couple, but only on multi-million mansions that copy the old Tudor or Euro Cottage designs.