Lush forests, medieval castles, quaint villages: sound like east Germany to you?

Up in the treetops we stare into the leaves of a rare beech forest from this bird's-eye-high walkway which we clanked up spiral stairs to reach. If Europe had been left to naturally seed itself then beech forests, such as this one in the Hainich National Park, 80kms northeast of Frankfurt, would carpet great swards of it, instead of man-sown pine forests and Tarmac.

While military manoeuvres often cause destruction, in this park its fire-powered neglect has created a beech-rich Unesco World Heritage site. The East German and Russian armies practised war in this natural phenomenon beside the old Iron Curtain, when this was part of East Germany, thus leaving broadleaf trees to flourish across the rolling hills.

In the nature reserve that this now is, experts have discovered various natural phenomena, such as finding out that a mysterious, reputedly wild cat actually does exist. They did this by pasting feline-favoured cod-liver oil to tree trunks. The cats came in the night, they licked and left their DNA.

As we lie flat-back on wooden chaise longues staring hypnotically up through a collage of blue sky and green leaves, I ask our guide what reunification meant to her. She is in her 30s, so for her it has resulted in a professional career, she says.

I have asked many people along my journey. The reactions depend a lot on age. Back then everyone was guaranteed a job, even if it meant overemployment, such as two ticket collectors on a bus. One woman in the town of Eisenach – which had a car factory since shut down – says those in their 50s at the time of change often never worked again.

Another, a teacher, says that now school students are more competitive and individualistic. In East German days they were better at teamwork, she says. It used to be family before the individual, she says: literally commune-ism.

I wonder what the former miners would think if they could see us stand-up paddling (involving standing on a surfboard and propelling yourself with a long oar) across a leisure lake that was created by flooding their former mine in Leipzig New Lakeland, just outside the city.

It has brought regeneration to the area where people are beginning to build holiday homes and taking advantage of sailing, wind-surfing and swimming opportunities as well as white-water rafting down man-made rapids.

We cycle around a lake watching locals take to the water, and being offered the rear view of a vast naked man slowly walking in to swim. One of our party who had driven in search of petrol returned with a tale of a car pulling up, three women getting out with their kit off and a man taking photos as they draped across the vehicle roof. 'Tis a long way from Ireland.

And yet the battle between Catholics and Protestants was drawn near here in Wartburg Castle. Comprising a string of Medieval, Romanesque and Renaissance buildings – with cobbled courtyards – it is perched defensively, magnificently on a plant-rich, rocky hill above the town of Eisenach, where the house of composer JS Bach can be visited.

They play Bach-era instruments for you at the museum but it is not completely dug into the past: you can sit in plastic globes and listen to music through headphones and cup cappuccino in the classically planted garden.

The classical link is not limited to Bach – Richard Wagner set Tannhäuser, his opera about heavenly and earthly love, in Wartburg Castle.

Up in a small stone castle room that overlooks the contoured landscape, Martin Luther wrote his German translation of the Bible. He came here having been "kidnapped" in 1521 from a street by castle resident Frederich the Wise to protect him from a law giving the right to kill anti-Catholics. In this room he translated the New Testament from Greek to German and produced the tome that still has consequences.

The town of Eisenach below is beautifully preserved, retaining its medieval flavour and feeling like the set of Beauty and the Beast, with its half-timbered and stone buildings.

We eat in a traditional, flagstone-floored restaurant called Gasthaus Storchenturm, where the meaty proprietor tells edgy tales with roaring punchlines to tables of diners. During dinner you get taken to a mini-play enacted by a man down a well-like hole – with no escape-steps out – enclosed in a small stone building out the back of the restaurant.

Depictions of past human horrors serve as entertainment before dessert.

We have another buxom meal at thick Gothic wooden tables in the Bastie area of the Saxon Switzerland National Park where waiting staff dress in traditional clothes to give tourists the "authentic" experience we apparently want. We are nowhere near Switzerland – the term is used semantically to mean romantic and hilly – and the teetering Tolkienesque towers of rocks and cliffs make for a dramatic affair.

Climbers and walkers trek through this park and – even if you are not going to spend days clambering across this magical landscape – it is worth walking a while, beyond the area that anyone arriving by bus can get to. Although even if you only make it to the sky-level, rock-top visitor platform, the views down to the Elbe and across the craggy spires will make you high.

We walk down through woods – another forest being encouraged to return to its deciduous destiny – to a flat ferry that crosses the river. We hire bikes and pedal down the Elbe towards the Czech border, stopping at the organic Helvetia hotel where, having been made giggly by fruit cocktails, we sit on a swing dangling from a tree – surrounded by candles flickering in the dusk – and sway towards the river.

The journey up through the former East Germany has revealed a country that has been heavily invested in but which still looks different from the former West, where seemingly all land has been cultivated. In the East there are still great plains, large fields of grass, and those vast preserved woods. Not everything survived the communist era – historic buildings were razed to make way for factories and other industrial fare. In stunning Leipzig, reunification came just in time, says a local: and yet she points to a spot where the old University Church was flattened in 1968. We are dining at the top of the Panorama Tower, a communist era, futuristic edifice, that has been put to brilliant use, giving views across the city, especially from the open-air platform dwarfed by sail-like electronic receivers and walls low enough to terrorise health and safety inspectors.

The decision to preserve, grow and make accessible the natural phenomena that survived in this land has made this formerly closed-off country one that is open to all sorts of discoveries.

Aer Lingus and Lufthansa fly direct from Dublin to Frankfurt daily.