Stumbling south from Berlin’s centre, as many night-owls do on the way to friends, another dive bar and a frothy beer, it’s easy to believe the old cliché that Berlin is a sea of grey. As Mitte spits you out and Kreuzberg starts to devour you, similar-looking buildings encircle the nocturnal wanderer. And when you look out of the window of the S-Bahn Ring Line trains that chug round Berlin’s periphery, the sprawl of concrete is immense – plattenbau tower blocks rise like crooked teeth above Lichtenberg and Marzahn. And on any day that isn’t sunny and mild, the city can feel as if it’s enveloped by a foggy gloom that isn’t helped by the Berliner Schnauze – the famed grumpiness of the locals.

But initial impressions can often be misleading. Look further, and you’ll see that Berlin is actually one of the greenest cities in Europe. In between all those squat apartment blocks, gardens crouch out of sight and parks give people space to be free; there are even beaches and lakes and wild woodlands – all within city limits. Because, when you examine Berlin with a microscope, you see what it really is: a city of gaps. These gaps provide homes for biergartens or sunbathing spots in summer. In winter, they become vegetable gardens or wildlife havens. Berlin is even hosting its own festival of flowers next year – the International Garden Exhibition, which takes place in a huge dedicated site in the old East Berlin district of Hellersdorf between April and October (iga-berlin-2017.de/en).

My green Berlin adventure begins in Prenzlauer Berg, where East Berlin’s bohemians lived under the GDR regime. Here, the Berlin Wall once sliced through the city, splitting lovers and families with its horrible heft. The Mauerpark is a former stretch of wall – wide and sloping. It smells of weed, reggae blasts out, couples smooch, basketballs are bounced. There’s a more austere memorial along nearby Bernauer Street with information boards and horrifying recreations of the wall’s death strip. The most poignant part is where the wall once chopped into an old graveyard.

There are so many parks in Berlin that once you start seeing them, it’s hard to stop enjoying them

Kollwitzplatz seems sunnier and friendlier – kid-friendly, with play equipment and gossiping parents drinking flat whites. At its centre stands a statue of the famous German artist Käthe Kollwitz, who was staunchly against war and violence. She would surely have approved of today’s liberal, peaceful, friendly and vibrant re-unified Berlin, a Berlin filled with Vietnamese restaurants and Turkish takeaways, with London exiles, Spaniards, American DJs and party animals from every corner of the world.

Some of the city’s green spaces are outright weird. The next day I find myself by accident in the Heinrich von Kleistpark in Schöneberg, south of the city centre. It’s a spooky place, haunted by ghosts of Nazi show trials held in the court building at its centre, and by the princes who came to relax here in the 1700s. It’s been a swish botanical garden and is currently a bit grubby and full of statues and colonnades which look incongruous because they ended up here after being moved from other parts of the city. There’s even a crazy apartment block called the Pallasseum, which pokes into the park, and a World War II bunker which is still intact. Teufelsberg is another strange sight in a green lung, and one of my personal favourites. The ‘Devil’s Mountain’ is all the rubble of Berlin from the war, piled high, with a former American listening station on top – hidden in the middle of the Grunewald Forest. Director David Lynch wanted to buy this place. It’s still derelict though, and curious sightseers explore the remains of the NSA’s listening domes and admin offices, which are dangerously crumbling but give a rare high lookout point in an otherwise flat city. To get in I have to break through a small hole in a barbed wire fence, pulse racing.

Best of Berlin

More to see in the city

Klunkerkranich

Situated on the roof of a shopping centre in trendy Neukolln, this secret boho bar offers superb views over the city, cheap drinks and live music.

Asisi Panorama

This interactive exhibition is probably the closest you’ll get to experiencing Berlin when the wall was up. Artist Yadegar Asisi has created a 1:1 scale panorama of the view from Kreuzberg to East Berlin in the 1980s which, when seen from the elevated viewing platform, comes to life in an eerily realistic way.

Tempelhof

An old airfield which is now a huge public recreation area where you can ride your bike down the old runway, and drink beers in a vast allotment.

There are so many parks in Berlin – once you’ve started seeing them, it’s hard to stop enjoying them. Treptower Park is perfect for games of softball or eating ice cream, while the huge Tiergarten at the city’s centre contains the odd war memorial on top of a huge plinth and the iconic Brandenburg Gate. It’s here that football fans gathered to watch Germany in the Euros on the city’s biggest big screen. The city’s zoo is attached to a corner of the Tiergarten and a cute canal runs through it too.

On the city’s outskirts, bucolic Berlin makes its case even more strongly. Despite visiting the city many times, I’d never been down towards the Lake District around Potsdam until this year. It is a revelation. At Wannsee there’s a huge beach with sand imported from the Baltics fronting onto the Wannsee Lake. It’s like a huge holiday resort hidden in the trees. On the way back to the nearest S-Bahn station at Nikolassee, in a forest clearing, hundreds of ageing men in leathers have gathered – this is biker country. And the place they head for when their huge bellies start rumbling is Easy Rider, opened in 1965 and the centre of West Berlin’s motorbike subculture. The freshly-fried schnitzel in a crusty roll fends off my own hunger for hours.

And not too far away is Groß Glienicke, a picturesque village in another clearing in the trees with an incredible history that was documented by Thomas Harding in his book The House by the Lake. The house in question once belonged to Harding’s Jewish family, and later in its life the Berlin Wall ran down the end of the garden, separating it from the lake. The house is currently being turned into a museum. I walk past the house, along the course of the wall, looking at the ducks on the tranquil lake, and thinking about the past. This Berlin is so quiet, so still, so green. The silence is suddenly broken by a commotion – two old ladies emerge from the lake after a refreshing afternoon swim and both throw me a friendly smile.

Getting There

Nightly rates at Hotel Oderberge start from £106, hotel-oderberger.berlin; Hotel Provocateur from £127, provocateur-hotel.com; and Art’Otel Berlin Mitte from £85, artotels.com

Norwegian Air offers one-way flights from £29, norwegian.com; See visitberlin.de/en for more information.