part of the battery's field of fire. Therefore, in the 1870s the Drop Battery was replaced by another gun battery further to the south-west: St Martin's Battery; it had three gun emplacements (designed to accommodate 10-inch RMLs) with ammunition stores in between them. In 1898 a further gun emplacement, the Citadel Battery, was built at the far end of the Western Outworks of the Citadel (the westernmost extremity of the site). It was designed for three 9.2 inch Mark X BL guns. Another battery was built at the same time to the south (South Front Battery), but it was short-lived. By this time the guns on St Martin's Battery were obsolete and it remained out of commission until World War II, when it was re-armed with three 6-inch BL guns. The Citadel Battery, on the other hand, remained operational until the dismantling of Britain's coast artillery network in 1956. Older features The Western Pharos On top of the Redoubt are the remains of a Roman Pharos, or lighthouse, which complemented the one that still exists in the grounds of Dover Castle. Both date from the 2nd Century AD, and would have been similar in design lighting the cliffs either side of the Roman Port of Dubris. The remains were lost during the first period of construction, but were re-discovered during the second period and restored to their original position as a rather shapeless lump of masonry. The foundations, though, are present in the room immediately below. Local names for the remains of the Pharos are the ‘Bredenstone’ or the ‘Devil’s Drop of Mortar’, and it was here, until 1804, that the Lords Warden of the Cinque Ports had their installation ceremony. It is likely that the name ‘Drop Redoubt’ originates from the local name given to the ruins of the Pharos. Knights Templar Church Between The Citadel and Drop Redoubt are the ruins of an 11th-century church with a round nave. Today Today, much of the site is open as a country park. The barracks have been demolished. The Citadel, formerly a young offenders' institution, was most recently used as the Dover Immigration Removal Centre, and so was off-limits until at least November 2015 when the centre was closed down. Many of the Citadel's original buildings remain preserved within. In 2018 the freehold site was put up for sale. English Heritage owns the Redoubt; the Grand Shaft spiral staircase is