St. Helena's fort at Ladder Hill
High Knoll Fort stands 584 metres (1,916 ft) above sea level and is the largest, most prominent and most complete of the forts and military installations on the island. It is located to the south west of, and overlooking Jamestown. It is designated as a Grade I Listed building and is one of the Seven Wonders of St. Helena.
The current fort was built by the Royal Engineers in 1874, but this structure incorporated an earlier fort on the site built in around 1790 by Governor Brooke. This earlier fort comprised a high, square structure with two outer towers and stone ramparts. On Read’s 1817 map this fort was named “High Knoll Citadel”.