(CNN) — Imagine walking through the streets of Madrid, the Spanish capital, and suddenly noticing small doors carved into walls, as if leading you to hidden worlds brimming with details. (Watch the video above)

The "secret houses" are one of the unique phenomena in the Spanish capital, sparking the curiosity of both locals and tourists, especially as they are linked to the character "Ratón Pérez," the Spanish version of the "Tooth Fairy."

Kuwaiti content creator Ali Al-Buloushi was among the lucky ones who saw them in person.

Al-Buloushi told CNN Arabic: "When I searched for them online, I initially thought the images were AI-generated, and I didn't believe they were real until I saw them with my own eyes."

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Despite their small size — no more than about 20 centimeters in length and 15 centimeters in width — these houses contain intricate details that mimic real homes, such as beds, tables, televisions, and small lights.

The Kuwaiti content creator explained that they are not tied to any practical use but are intended to create a visual experience that blends reality and fantasy.