The elevated rail viaducts are a major physical presence across South London. This part of London largely sits on 'Lambeth and Thanet sand', resulting in ground conditions that were historically more challenging to tunnel through than the clay that characterised much of North London's geology. Coupled with this is the proximity to the River Thames, where the neighbourhoods were low lying and marshy, so building elevated infrastructure was a more practical solution.
The area covered by this brief lies along the viaduct between Southwark tube station in the west and Southwark Park in the east. Here the characterful brick viaducts connect and dissect several distinctive and different neighbourhoods.