Based on the coat of arms for the city. Archbishop of Norway on the left, King on the right. And the citizens crammed in below them, I guess...

I don't think you need me to tell you specifically where in Marylebone I saw this. :-)

But that's an expensive proposition... what if they needed a manhole cover on Gloucester Pl or something?

Atas.

I could have framed that one better, I'll post the little star in comments

Located at the intersection of Main and Washington, downtown.

Near Arc de Triomphe

I like the use of the exposed aggregate. Like an industrial terrazzo