After 1858, a further 'Detached Bastion' was built immediately to the north of the North Centre Bastion (which was itself rebuilt and strengthened), to the designs of Captain Edmund Du Cane. (The bastions enabled flanking fire (by both muskets and artillery) along the length of the North Line.) At the same time, the Citadel was extended to the west (the 'Western Outworks') with further casemated barracks provided within the new ramparts. Also at this time, following the Royal Commission of 1859, the North and South Lines were strengthened and the North-East Line rebuilt on a different alignment, more effectively closing off that end of the site between the Drop Redoubt and the cliffs. Furthermore, the North Entrance was rebuilt and strengthened (necessitated by the rebuilding of the Lines); it was approached by way of a twisting path through the tenaille and lifting and falling bridges across the ditches. A new South Entrance was also provided to the south (built where the South Military Road crossed a new extension to the South Lines, close to the junction with Citadel Road). Also known as Archcliffe Gate, this monumental stone gatehouse was demolished in the 1960s.