A new TV documentary is expected unveil secrets of a giant former fortress to the world.

A film crew is to expose the vast closed site of The Citadel in Dover, which dates back hundreds of years.

The area, originally part of a giant Napoleonic defence, is gradually to be redeveloped – with plans including a hotel – as part of a multimillion-pound project.

David de Min, boss of the site’s owners Dover Citadel Ltd, revealed news of the TV project on a post on his Facebook page.

It shows an initial clip by the director who will eventually take on the project, Ravi Ajit Chopra.

Mr de Min’s post said: “Here is a teaser of the TV documentary that has recently received the green light to film a special of the Citadel and Western Heights.

“We have been signing some incredible partners that all form part of the larger vision, which I look forward to sharing soon as we continue to make progress.

“Not many people see what goes on behind the scenes with all the moving parts of this hugely exciting project but it has been very rewarding seeing it all come together after all the years of planning.”

There are no details yet as to when the documentary will be filmed in full and eventually shown.

Mr Chopra is known for directing the 27-minute science fiction drama Cognition, which came out in 2020.

It starred Andrew Scott, Jeremy Irvine and Lucy Russell and won awards across the world such as at the American Independent Film Festival, South London International Film Festival and the European Cinematography Awards.

The Citadel is part of the Western Heights, the biggest Napoleonic fortifications in the country.

The area continued to be used as defences during both world wars and from the 1950s and 2010s was used in turn as a prison, borstal and immigration removal centre.

It is almost always closed to the public and only had its first ever open day in June.

Gradual major redevelopment is planned for the site including a hotel in the Officers’ Quarters, restaurants, art galleries and small business units.

Planning permission has this year been given to reuse two of its former prison blocks, Sandwich House and Hastings House.

These would be adapted for overnight stays by council and emergency services workers during training sessions.