• Free, but you must book ahead on the Metro de Madrid website, and each guided group is capped at 28 people
• A 30 to 40 minute visit, short enough for kids who like trains and tunnels
• Open Friday to Sunday only, so plan it as a weekend add-on near Plaza de Chamberí

Chamberí is a Metro station from Madrid's first line, closed in 1966 when trains got longer, and left almost untouched. The platforms still show their original tiled walls and vintage advertising posters from the 1920s to the 1960s, designed by architect Antonio Palacios. A 30 to 40 minute guided visit walks you through the tunnel and platforms.