Age-restricted playgrounds
Most playgrounds are designed for one of three age groups: infants and toddlers (6–23 months), preschoolers (2–5 years), and school-age children (6–12 years). They tend to lack infrastructure for teenagers, like hangout spaces, exercise equipment, or skateboard ramps. And it’s not only a problem of lack of fit: in 2021, an ordinance passed in Largo, Florida, banned any adolescent over the age of 12 from accessing playground equipment unless accompanying a younger child.

High schools typically lack hallway seating and communal gathering spaces like courtyards or else keep communal gathering spaces off-limits, restricting student socialization to the class-room, the cafeteria, and the bathroom. The recently rebuilt Fruitport High School in Michigan was designed with the most profoundly antisocial architectural priority of all: preventing school shootings. With curved walls that reduce sight lines and cement blocks in the hallways for students to hide behind, Fruitport is the first high school designed specifically to maximize safety from gun violence.

Blue lighting is a classic example of hostile architecture: frequently installed under bridges and in public bathrooms, it disincentivizes intravenous drug use by making it difficult for users to locate veins under the skin. Perhaps inspired by the relative success of blue lighting, officials in Lancashire, UK, have experimented with another color: pink lights that put adolescent skin blemishes in stark relief, theoretically disincentivizing youths from congregating together where their flaws might be more visible to peers.