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Two architects, on either side of the debate, discuss whether hostile architecture is ruining cities
It looks like something designed to stop inmates from escaping a prison complex. But this shocking photograph of metal spikes covering the branches of a tree was actually taken in a wealthy residential suburb of Bristol, England. Their purpose? To prevent birds from perching on the branches, and defecating on the cars below.
Despite outrage surrounding the spikes exploding on social media this week, they will remain. “There’s nothing the council can do because it’s on private property and there’s no tree protection order in place,” a spokesperson for Bristol City Council told CNN.
The rise of hostile architecture
This installation is a prime example of hostile architecture – a controversial type of urban design usually aimed at preventing people from using public spaces in undesirable ways. It can come in the form of spiked or sloped benches, bolts installed on shop doorsteps and windowsills, and even water features that operate at surprising intervals on flat surfaces.
While use of design to block homeless people from finding a place to sleep or young people from skating in public angers many people, others feel it’s a necessary measure to secure public safety.

CNN invited architect James Furzer, whose designs try to combat hostile architecture, to debate this issue with Dean Harvey, co-founder of the Factory Furniture: a company that produces many of the offending benches.
Read: Is “female architect” an offensive title?
Here’s how their Skype conversation went.
You’ve both seen the shocking tree spikes in Bristol. What is your reaction?
James Furzer: This is totally hostile architecture. Hostile architecture doesn’t affect humans only – the landscapes we design can also be manipulated to deter all sorts of acts. It’s such a shame that it now applies to nature.
Not only does it look unattractive and aggressive, it shows the selfish nature of society and its thoughts on the environment. Has anyone considered who takes the blame if children wish to playfully climb the trees, unaware of the barbaric devices situated on top of the branches? (Or) if a branch falls, with an unsuspecting person relaxing beneath?
Dean Harvey: My initial thought is that this cannot be considered an extension of hostile architecture: spikes have been used to protect damage to stonework from bird droppings for many years.
This is an extension of pest control. I think the issue here is the damage to the ecosystem of the tree and the aesthetic problem it poses. It’s totally unnecessary. A tree is a natural object, and this (the addition) is a complete eyesore. The time and effort they spent putting those spikes on trees is probably totally outrageous in comparison to any actual problem.
How do you define hostile architecture?
Dean Harvey: