One interesting moment in the streets of London - The boundaries

This is a street crossing on Clerkenwell Road in Saffron Hill near where I live in London.

The boundary lines of materialities in the city. For instance the North and South bank near London Bridge. On the South Bank, the representative architecture are the London City Hall designed by Foster+Partners, the Shard designed by Renzo Piano and the ... These buildings have exposed steel structure or glass cladding on the exterior.