In the story, the body of a junior clerk named Cadogan West is found on the tracks outside Aldgate, with a number of stolen plans for the Bruce-Partington submarine in his pocket. It seems clear enough that “the man, dead or alive, either fell or was precipitated from a train.” But why, wonders Holmes, did the dead man not have a ticket? It turns out that the body was placed on top of a train carriage before it reached Aldgate, via a window in a house on a cutting overlooking the Metropolitan line. Holmes realises that the body fell off the carriage roof only when the train was jolted by the dense concentration of points at Aldgate.
Aldgate is a London Underground station near Aldgate in the City of London. The station is on the Circle line between Tower Hill and Liverpool Street, and is the eastern terminus of the Metropolitan line. It is in Travelcard Zone 1.
Royal assent was granted to the North Metropolitan Railway Act on 7 August 1854. Due to the cost of land purchases, the Metropolitan Railway’s eastward extension from Moorgate Street was slow to progress and it had to obtain an extension of the Act’s time limit in 1869.
The route first proposed ran south from Moorgate to Cannon Street, but this was soon amended to the present alignment to allow connection with three additional termini: Liverpool Street, Broad Street, and Fenchurch Street. However, this change also forced an awkward doubling-back at Aldgate, reducing the desirability of the line for local traffic and greatly increasing the cost of construction due to high prices in the City of London. Construction was also complicated because the station was on the site of a plague pit behind St Botolph’s Aldgate which contains an estimated 1,000 bodies. During the extension of the railway to Aldgate several hundred cartloads of bullocks’ horn were discovered in a layer 20 ft (6.1 m) below the surface.
A terminus opened at Aldgate (Aldgate station, with its entrance on Aldgate High Street) on 18 November 1876, initially for a shuttle service to Bishopsgate before all Met and District trains worked through from 4 December.
A southbound extension to Tower Hill opened on 25 September 1882, completing the Circle (line). Services from Aldgate originally ran further west than they do now, reaching as far as Richmond.
The train shed of 1876 survives, hidden from the street by the later station frontage building erected in 1926. This was designed by Charles Walter Clark the Metropolitan Railway’s chief architect between 1911 and 1933.
The station building has a six-bay façade clad in white faïence with original features including 1920s shopfronts with green marble and pink granite stallrisers, a half-hexagonal canopy of glass and metal suspended by elegant metal ties, leaded light first floor windows, dentil cornice, two ornamental lamp brackets and a frieze bearing moulded lettering and the Metropolitan Railway monogram.
Aldgate became the terminus of the Metropolitan line in 1941. Before that, Metropolitan trains had continued on to the southern termini of the East London Line.”