On November 9, 1989, the scenes of jubilant people queuing to cross the Berlin Wall from east to west were beamed into our living rooms.

The infamous wall that divided a city for 28 years had opened and the people of East Berlin swarmed, cheering, into the land of freedom and capitalism that was West Berlin, some with as many of their possessions as they could carry.

More than 100,000 East Germans had tried to escape the regime, and at least 136 people were killed trying to make their escape, many shot by border guards.

Tomorrow, the 25th anniversary of the historic moment the wall fell is celebrated, and how times have changed. The Trabant-driving Eastern Germans or Ossis, as they were known by their western counterparts, many of whom were desperate to escape the east to enjoy western luxuries, would have laughed at the notion that a quarter of a century later East Berlin is now the place that many flock to, the grand Communist boulevards seen as a desirable place to live.

The pace of gentrification of the east has been fast - no more the miles and miles of grey buildings, as many streets look like they have featured in a Dulux advert, so colourful are some of the old facades. The sight of cranes, scaffolding and the noise of construction is also never far away.

In the run-up to this celebration, I am here to see how the city and its people have changed. I am staying in one of the countless boutique hotels which have sprung up in the former eastern Mitte district. The chic i31 Hotel, complete with its German-style inner garden, is just a short walk from the new main train station, Hauptbahnhof. Opened in 2006, the giant glass construction took over from Zoo Station in the west and Alexanderplatz in the east and is a milestone in the binding together of the city's very different parts.

I head south towards Rosenthaler Platz, where cafes, restaurants and bars abound in this popular gentrified neighbourhood, then along the trendy Torstrasse which has been transformed in recent years into a street of chic boutiques and bars.

Stopping off in the cafe Zur Rose is like stepping back 30 years in time. The Formica-topped tables, mismatching chairs and kitsch wallpaper make this one of the nicer old eastern experiences. This Ostalgie - as the nostalgia for the old east is known - is all around. For some people it's a genuine desire to go back to the old regime of no unemployment, a state that looked after you and the old eastern brands of food which disappeared along with the country.

But for others, Ostalgie forgets the reality which for some was life or death. Hundreds of people were killed trying to escape over or under the 3.6 metre high wall to the west, while 5,075 are known to have made a successful bid for freedom at points along the 155km boundary.

I head to Berlin on Bike, a cycle tour company housed in an old east brewery which is now a cultural centre in the trendy Prenzlauer Berg district to find out more about the dark side. I'm taking the Eastern Tour, so first we head out to the wall memorial at Bernauer Strasse, where some of the original wall still stands, while missing parts are represented by huge iron bars.

In one of the few political events planned to mark the milestone, tomorrow German Chancellor Angela Merkel will open the renovated Berlin Wall Memorial Documentation Centre at this site, with eyewitness accounts and readings planned.

In the park the memorial to those who lost their lives brings the reality home, with pictures of many who died in their break for freedom. An image of one little girl highlights the brutality of the East German regime, which would stop at nothing to prevent citizens escaping. This monument sits in the garden next to the 1.4km former border strip which reveals the grey prison-style walls which kept the east and west divided and documented the timeline of events which led to its demise.

Back on two wheels and cycling on the kind of bike lanes we can only dream of in Scotland, we head along big boulevards to the eastern periphery of the city where the Stasi, or state security, prison was located. Now a memorial, it was where political prisoners (or anyone who did not live according to party guidelines) were taken, tortured and held.

My guide Andre tells me the youngest boy brought here was just 14 after he questioned the country's politics in his classroom. Nine of today's guides are former inmates of the prison, known as Hohenschoenhausen.Next we head a few kilometres south to the Ministry for State Security HQ, past miles and miles of grey prefabricated buildings. Cycling under a nondescript archway in one of them takes us into a courtyard described as "a notorious compound".

It's where the Stasi orders came from - where they "fought the enemies of the Socialist Unity Party of Germany" with their Marxist-Leninst ideology - and also where the infamous Stasi files are held. Throughout the regime's 40-year history, the secret police spied on, bugged and followed people they termed citizens of interest and their findings were meticulously documented and filed in an adjoining building to the headquarters. With 111km of files and more than 1.7 million photographs in the archives, even today German citizens can apply for their Stasi files.

"I applied to see if they had a file on me but there was none," says Andre, who is from a village in the east. "But there are files on my parents and my grandfather." It was a daily fact of life in the east and one that continues to astonish and fascinate. He says they asked his grandfather to spy but he refused, so this led to his observation. Blanket surveillance was made possible with 91,000 Stasi workers aided by the 189,000 spies known as unofficial collaborators.

We head along the wide and grand Karl-Marx Allee back to the centre of Berlin. Much of the old eastern boulevard is now protected by heritage laws and the flats are now outwith the financial reach of the workers they were built for.

At the end of the row of grand apartments, grey prefabricated towers stand next to an area of grass with concrete stones.

"This is where a 3.5 tonne statue of Lenin stood," says Andre. City officials removed the granite head in 1991 after the fall of the old regime, using a crane as it was so heavy, and buried it in Koepenick Forest in the outskirts of the city.

"Now they want to use the head as part of an exhibition on Communist and Nazi monuments of the past but first the city officials said no, then they said yes but now they say they've lost it. Someone must know where they buried it. You can't lose a 3.5-tonne head!"

After cycling 22km, I wander down to the east's gallery district Auguststrasse. This area became a huge draw for artists when the wall came down, with cheap rents and big spaces, but the artists are now returning to the west as the rents as now so expensive in this area.

I stop off at a former Jewish girls' school which is now a major arts centre that houses a Michelin-starred restaurant, but I head into its neighbour for a quick bite, the New York-style deli Mogg & Melzer which serves Jewish-style dishes in keeping with its heritage. Art and history seem to be everywhere in Berlin, so keeping on an arts theme, I take the underground south east to the East Side Gallery. At 1316 metres long, it is the largest remaining single piece of the wall to stand as it was, except for the fact that artists were invited to paint on the east side of the wall which was forbidden under the old regime. Artists with a Berlin connection from all over the world were hand-picked to paint on a section - including Margaret Hunter from Ayrshire, who has lived in this city for 30 years. Her double head painting represents the two faces of Germany, while famous images include the Trabi bursting through the wall and the Honecker and Brezhnev socialist kiss.

So 25 years on from reunification, how have the people reunified? East verses west still seems to be an issue for older generations at least, and the joining of two very different cultures certainly appears to be taking time in stark contrast to the simple act of bulldozing a wall. When I meet Martin, a West Berliner friend who was six when the wall went up, I realise this is something he never mentions until asked.

He says: "I am a West Berliner by chance - all my father's family were in the east but my dad had a job in the west and moved us there. When the wall went up it took him about 12 years to come to terms with the fact that we had to apply for a permit to see my grandfather and aunts once or maybe twice a year at most.

"For me, it was just normal because that was always the case."

He adds: "I would still never drive in the east because of the trams - we don't have them in the west and I was never used to that."

Indeed, a recent study found that Germany is still very much divided by a social wall, despite the physical wall's demise 25 years ago. Another friend I ask confirms this, adding: "I have friends in the east and friends in the west but I would still never mix the groups."

For younger generations the lines seem more blurred, the memories of a divided city less distinct.

Berlin will celebrate the 25th anniversary by lighting up the path of the former wall with a light installation of 8000 balloons which will stretch past monuments such as the Brandenburg Gate, Potsdamer Platz and Checkpoint Charlie.

The bricks may be down but some of the emotional barriers and differences it created will take generations to fade from the psyche of many.

However, that barrier and the history which seems to be awash in the streets - from the double brick line that zigzags its way throughout Berlin to show where the wall once stood to the idiosyncrasies of a once-divided city that has two of everything - make walking along the streets of this city an endlessly fascinating and sometimes jaw-dropping journey of discovery. n

For all 25th anniversary Berlin Wall events www.visitberlin.de/en