Edinburgh
Royal Mile - wealthy people lived on this street
Behind the Royal Mile poorer people lived
Edinburgh Castle was built on a volcanic plug for DEFENCE.
It didn’t grow beyond the Royal Mile due to the surrounding hills, and to ensure it was safe.
Defence no longer became an issue, and the city spread.
This was made possible by building the Mound,
And the bridges
It has now grown to be a huge city. It cannot expand any more due to tight planning regulations. This is an attempt to preserve the Green Belt.