The zoo

Zoo visited by Dursleys where Harry's magic causes glass to vanish.

The zoo, specifically the Reptile House at London Zoo, bursts into the Harry Potter series in a spectacular display of Harry's uncontrolled magic during a mundane family outing with the Dursleys. In a fit of accidental magic triggered by Dudley's bullying, Harry vanishes the glass of the snake enclosure, freeing a boa constrictor that subsequently coils around Dudley in revenge before slithering away. Though this incident marks the zoo's sole appearance across the entire seven-book saga, it serves as an iconic early emblem of Harry's burgeoning wizarding powers and his irreconcilable rift with the Muggle world, never revisited in later adventures.