Hostile Architecture

Wikimedia

In the above photo (from Wikimedia): “This is an image of a concrete wall studded with metal plates to prevent grinding in sports such as skateboarding and rollerskating.”

Wikipedia defines hostile architecture as:

"...an urban-design strategy that uses elements of the built environment to purposefully guide or restrict behaviour. It often targets people who use or rely on public space more than others, such as youth and homeless people, by restricting the physical behaviours they can engage in.^[1] Also known as defensive architecture, hostile design, unpleasant design, exclusionary design, and defensive urban design, the term hostile architecture is often associated with "anti-homeless spikes" – studs embedded in flat surfaces to make sleeping on them uncomfortable and impractical, this form of architecture is most commonly found in densely populated areas. ..."