Madrid opened Spain's first metro line in 1919 — and Chamberí station, closed since 1966, survives beneath the street almost exactly as it was, complete with original tiled advertisements.
Chamberí station opened on 17 October 1919 as one of the original stops on Madrid's first Metro line. As the network grew and trains lengthened, the station's central platform became too short to safely serve longer trains, and rather than being expensively rebuilt, it was simply closed in 1966 — trains have run straight through it, without stopping, ever since. Sealed off from daily use, it survived largely undisturbed for decades, an accidental time capsule of 1920s Madrid.
Original ceramic-tiled advertisements for products long discontinued, period ticket booths, and the platform architecture exactly as commuters would have seen it a century ago. It reopened to the public as the Andén 0 ("Platform 0") museum in 2008, with a short film and small exhibition on the history of Madrid's Metro alongside the preserved station itself. A glassed viewing area also lets you watch modern trains rush through without stopping — a genuinely striking detail once you know the history.
Entry is free, but visits typically run as timed guided tours with limited capacity, so it's worth checking current opening days and reserving ahead rather than turning up unannounced — the museum doesn't operate every day of the week.
This is one of Madrid's better "hidden gem" visits precisely because it's under-visited relative to how good it is — a rare case where the low profile is a genuine advantage, not just a marketing line.