When you walk across Dover’s Western Heights you are walking on history.

Apart from providing splendid views of the town, valleys and the English Channel, you come across the remnants of fortifications dug into the steep hillsides dating back to the 18th century.

The area, now a 128-acre nature reserve, towers above the town centre and can be seen for miles, including across the valley from Dover Castle.

But the gems are hidden with the Western Heights’ long trails.

The three main areas – the Grand Shaft, Drop Redoubt and Citadel – are usually closed to the public but the latter two had rare full openings for the public at the weekend.

The great advantage of this area is that you will never tire of it as there are miles of trails, with the hilltop ones giving you breathtaking views,.

It is one of my favourite areas for hillwalking in Dover along with Dame Vera Lynn Way, which takes you to Langdon Cliffs to the east of Dover.

The steep hillsides of the Heights keep you fit, as I found when I was on furlough for eight months during the pandemic in 2020.

The extra time I had to clamber those slopes helped me drop from 18st 7lb that March to 16st 1lb four months later.

There is that immense sense of exhilaration when you finish a 60 to 90-minute march that keeps you on a high for hours.

There are three key trails stemming from the three main areas.

The longest route, the two-mile Citadel Walk, takes you to the top alongside the outer edge of the enclosed fortress and overlooking the neighbourhood of Aycliffe and the A20.

Close by is also the fort’s most impressive building, the 19th century Officers’ Quarters.

On the way are remnants of small fortifications such as at the Citadel Battery. A long concrete path takes you on a tangent from that trail along the hilltop heading towards Farthingloe.

That area was used to house workers building the Channel Tunnel at the turn of the 1980s and 90s.

Generations of children in the neighbouring Clarendon and Westbury estate were able to enjoy a small play park on the lower slopes of the Western Heights.

This was just up from Clarendon Place and complete with swings and a roundabout.

That is long gone – but further up that hill remains a small football pitch, which has been used by locals when it has not been left overgrown.

There are also entrance paths to the hills from Maxton, so locals there can also scramble up for a walk.

Good hard walking shoes are a must anywhere on the Western Heights, as most paths are rough and uneven.

That's why it is never advisable to walk there in darkness as there are absolutely no man-made lights, so there is a risk of missing your step and falling.

As you are far from roads it is much harder for rescuers to find you. Even a helicopter would struggle to locate you if you are inside the hills’ dense patches of woodland.

Dry ground is also an important condition as the paths can become slippery on damp winter days.

Those of us no longer that young and agile need to take great care going down the steep slopes. In such cases a walking stick or Nordic poles would help you keep your balance.

Such implements would also help you beat back brambles in wooded areas.

The Western Heights were seen as an ideal natural fortress where fortifications could be dug into the steep slopes.

For centuries Dover Castle could be used to defend the area on the eastern side of the Dour Valley, where the town centre now is.

But there was nothing to protect the port on the western flank, with the hills there only used as farmland.

The first fortifications were put in place in 1779 during the American War of Independence when there was the threat of invasion by that country's allies – France, Spain and Holland.

The defences were further beefed up from 1804 as Napoleon's forces threatened to attack. It was from then that the earliest forms of the Citadel and Drop Redoubt were linked by ditches.

These are 29 to 49ft deep, which can be seen to this day. Additions and modernisations to the defences to continued to be added to and updated up to the Second World War.

The centuries-old walls and buildings remain rock solid, which is remarkable as they were designed and constructed with what we would view as prehistoric engineering technology today.

Lara Fraser, spokeswoman for the present owners of the Citadel, Dover Citadel Ltd, told KentOnline: “These structures they are immense and skilfully built. There was obviously a lot of knowledge at that time that we don’t give credit to.

“There is nothing taking these buildings down. They have been through wars and they are still standing and still in really amazing condition.”

Phil Eyden is a volunteer for the Western Heights Preservation society, which organises open days at the Drop Redoubt and the Grand Shaft.

He said: “The Western Heights is the biggest Napoleonic fortification in the country. It’s two-and-a half times the size of Dover Castle with its grounds.

“With the Drop Redoubt we can have the public visit 80% of it. Two years ago it would have been 40%. Slowly, surely we are protecting and opening up what we can.”

The Drop Redoubt is usually closed to the public but has monthly tours in the summer period, the next being on July 16.

There are also two annual open weekends. The next is on September 16 and 17 and the previous one was at the weekend. These are all organised by the Western Heights Preservation Society.

Usually the public can only circle the block of that fort via one of the few accessible dry ditches

But at the weekend one of the huge block’s iron doors opened up and visitors climbed a steep staircase to find the hidden world of the rooftop fortress complete with casemates – firing positions.

There was a guest appearance by Jason Salkey (Rifleman Harris) from the Napoleonic Wars TV dramas series Sharpe that starred Sean Bean.

He said: “The fortifications are incredible and great structures. There are lots of nooks and crannies here to explore.”

The event also had a mock gun battle with members of Dymchurch’s Day of Syn Society acting as 18th century smugglers and soldiers from the period.

The scenario was that the smugglers were rescuing a child poacher who was sentenced to deportation to Australia.

The Citadel was used by the prison service from the 1950s as both an adult jail and borstal and was an immigration removal centre from 2002 to 2015.

Today major redevelopment is planned for the site including a hotel in the Officer’s Quarters.

It had its first ever open day on Saturday where people were able to view its four imposing prison buildings, still intact, and an art exhibition.

David de Min, chief executive of Dover Citadel Ltd, said: “This is the first open day in the Citadel’s almost 300-year history.

“We’ve owned the site for two years and it’s the first time anyone has gained access to it so from the locals there has been a lot of interest.

“The Citadel is one of the hidden gems, in the Western Heights. Some people in Dover don’t even know about it.

“We’re looking forward to having more open days.”

The 140ft Grand Shaft is open to the public at least once a month from March to November.

This was created as a spiral staircase so that soldiers could quickly move down from the then Grand Shaft Barracks to the Harbour if it was attacked by enemy forces.

In June 1993, I abseiled down it for charity.

For those who haven't tried it, the most sickening feeling is tipping over the edge backwards when your instincts are screaming at you not to.

But I survived it and continue to walk on the solid ground of the Western Heights.

How to get to the Dover’s Western Heights

By bus: To the Pencester Road terminus and then a Number 64 bus to the Western Heights or on foot uphill along North Military Road.

By train: To Dover Priory Station and the Number 64 bus from Pencester Road or on foot via steps between Folkestone Road and North Military Road.

By car: From the A20 at Dover via the Western Heights roundabout and South Military Road. There are free car parks at St Martin’s Battery, Centre Road and North Military Road.