A ventilation shaft attached to a bunker buried beneath the Folimanka Park in Prague became an urban canvas for a group of unknown street artists. They transformed the above-ground bit of abandoned bunker into one of the world’s most famous robots: R2-D2.

The anonymous artists went beyond merely painting the old structure. They added two concrete pieces to either side of the concrete dome, allowing it to resemble the shape of the beloved droid. They also added fine details, like the restraining bolt featured in the movies.

Surprisingly, the bunker’s Star Wars transformation went unnoticed for up to a week. The piece is not an official, city-sanctioned decoration, but it seems it will remain.

The Mayor of Prague 2 Municipal District, Jana Černochová, has said that although illegal graffiti is not supported, the decor on the shaft is an improvement to the unsightly vent and no action will be taken by the authorities. Some feel it’s an appropriate addition, as Czech author Karel Čapek was the first person to introduce the world “robot” into popular culture.