If you've ever traveled on the Piccadilly Line in London, you may have noticed that on the stretch between Green Park and South Kensington, the north-facing tunnel passes twice to a particular dark gray to charcoal black. I was always looking for those gray bricks when I brought the Tube back to Hammersmith. It was because I was obsessed with the disused stations, or "ghosts," and that on that stretch were two of the most distinguished: Down Street and Brompton Road, both of which were closed in the 1930s.

Down Street is of particular interest, having served in the following decade of bunker at Winston Churchill during the war. As a train station, it had hardly been used after it opened in 1907. It was too close to Green Park (then called Dover Street) and Hyde Park, and was located in a sparsely populated area. The trains often did not even bother to stop there, and it definitely closed its doors to the passengers in 1932.

Dozens of London underground stations have been closed over the years for reasons of infrequent use or rationalization, but their remains are also known as "ghost stations". One of them is King William Street, near the current Monument Station station, which was the original terminus of the City & South London Railway (now the southern stretch from the north line). When it opened in 1890, it was the first deep underground railway in the capital, but its life was cut short in 1900 when the line was redirected to Bank. Although the building was demolished, the platforms remain in place and a plaque commemorating its short life is visible today on Monument Street.

Another is Marlborough Road on the Metropolitan Line. It was hardly used by passengers, except during the cricket season, because of its proximity to Lord's. The knell occurred in 1939, after the opening of nearby St John's Wood. The building remains and housed until 2009 in a Chinese restaurant. It now contains an electrical substation supporting the metropolitan line.

The king of all the ghost stations of London is the most recent: Aldwych, formerly known as Strand. Opened in 1907, it was the terminus and the only station on this curious stage of the Piccadilly Line, which mainly transported theatergoers to and from Holborn. Over the years, the station has never seen many passengers and was the subject of many threats of closure before the end in September 1994, when it was decided that the replacement of lifts was not guaranteed. .

The station and the street building remained, with a facade of its original name installed. Since its second platform was closed in 1917, it was used by filmmakers looking to recreate generic scenes from Underground. He made his film debut in The kind armed man (1952), and later presented in The krays (1990) and Patriots Games (1992). Aldwych has since played in V for Vendetta, 28 weeks later and the drama of the BBC Sherlock.

When I had the habit of taking the no. 15 bus between Strand and Tower Hill, the empty view of Strand would spark the reverie of Harry Potterfantastic ghost trains, or passengers now dead and gone. The same goes for the Tower Hill building housing a Pizza Express, as this building was until 1967 the Mark Street subway station.