The hill presents as a dark-sided mass that towers over the western parts of the Low Weald and south-west Surrey.

There is no village or hamlet on Blackdown although it lies approximately equidistant from the railway town of Haslemere 2 miles (3.2 km) to the northwest, Fernhurst to the southwest, and Lurgashall to the southeast.

The lane keeps to Arthur Paterson's description in 1905: Trees meet overhead, copsewood surrounds it, and later, it is hedged by high sandy banks thickly overgrown with plant and scrub; squirrels and rabbits, and all other small woodland creatures, disport themselves over it.

The National Trust now carries out a programme of tree-felling and controlled burning to maintain and regenerate areas of open heath.

The pine- and heather-covered slopes are owned by the National Trust and have many paths and organised walks supported by volunteers, the local authorities, charities and guidebooks.

Although the exact date of his visit is unknown, it was probably during 1644–45 when he went to assist the Earl of Essex and Sir William Waller during the campaigns in the west of England.

As well as Aldworth House on the steep eastern flank and Foxholes (which together formed the estate of Alfred, Lord Tennyson), there is a range of architecture, especially in Victorian and turn-of-the-20th-century, rustic styles (such as Arts and Crafts).

Because of its elevation, from 1796 to 1816 Blackdown hosted a shutter telegraph chain station, which linked the Admiralty in London to the Royal Navy in Portsmouth.

Keen to escape the summer "trippers" who came to his Isle of Wight home, Farringford House, Tennyson purchased Blackdown, and built Aldworth in 1869.

While on approach to Heathrow on 4 November 1967, the Caravelle descended far below the flight level assigned to it and flew into the southern slope of Blackdown Hill in West Sussex, killing all 37 on board.

The crash also killed a flock of sheep, damaged parts of the roof of Upper Black Down House and destroyed a garage.