Summarised from report:

This gallery and its casemates, situated behind the east counterscarp of the North-West Bastion, formed part of the Napoleonic design, but construction did not take place until 1853-55. From the Right Flanking Casemates, a gallery descends twelve steps eastwards to a quarter-landing, then thirteen steps northwards to a 17.15m level section leading beneath the North Ditch. Off the east side, a ventilation shaft opens. The gallery then rises over a distance of about 21m to a short level section off which the southern casemated gunroom opens to the west. Then begins a long shallow descent - some 80m in all - interrupted by a short level section at the second and identical casemated gunroom and incorporating slight westward shifts in alignment before terminating at the Counterscarp Casemates. (1)

Detail of this structure appears on a plan dating to 1871 which shows all of the works which were undertaken under the reccomendations of the Royal Commission, though this gallery likely pre dates this plan by about 20 years. (2)

<1> English Heritage, 2004, The Western Heights, Dover, Kent: Report No. 2: The Citadel (Unpublished document). SKE17690.

<2> Captain H S Palmer (?), 1871, War Department OS 1:2500 Sheet LXVIII.15, revision of 1871, annotated with positions of magazines in the Citadel in 1877 (Map). SKE51524.