The Hardy Monument stands 72 feet high (22 m) on the summit of Black Down in Dorset, erected in 1844 by public subscription in memory of Vice Admiral Sir Thomas Hardy, a commander at the Battle of Trafalgar.
Admiral Hardy lived in Portesham and his family owned the Portesham estate which stretched from the middle of Portesham to Black Down. The site for the monument was chosen because the Hardy family wanted a monument which could be used as a landmark for shipping. The monument has been shown on navigational charts since 1846 and is visible from a distance of 60 miles (97 km).
The monument was designed to look like a spyglass, as Admiral Hardy would have used on board ship. Its eight corners are aligned with the compass points. Viewed from the ground the corner to the right of the lightning conductor points due south. The bench mark on the northwest face denotes the altitude of Black Down at 780 feet (240 m).
The heathland surrounding the monument was designated a Site of Special Scientific Interest in 1984, when the Nature Conservancy decided that the geology of the area was very rare.
Information courtesy of Wikipedia