DAVID KILLICK  visited Berlin after the wall fell. Twenty years on he finds a city transformed, but ghosts from the past still linger.

  'Angela Merkel, don't betray us on climate change!" proclaims the protest banner in front of the Brandenburg Gate. Demonstrators have erected little models of houses with slogans such as "Climate change refugees" and "Greenwashing - shame on you!"

  It's just a small demo, but 20 years ago it would have been impossible.

  This was East Berlin. Protest was punishable by imprisonment or death.

  I had stood in the same place on New Year's Eve, 1989. Just over a month earlier border restrictions had been relaxed and the world had watched amazed as thousands of East Berliners streamed through the crossing points to taste freedom in the west.

  West Berliners had climbed the hated wall and reached down to shake hands with East German border guards, and were hammering and chipping at the wall itself.

  I, along with a few hundred thousand West Berliners, stepped off the S-Bahn at the Friedrichstrasse railway station, and passed unchallenged into East Berlin. The crowd in front of the gate celebrated with fireworks as the new year dawned, promising a new era of freedom and opportunity.

  At the time I thought that the process would take a generation, and so it has proved. East Germans' dreams of wealth and access to BMWs and Mercedes-Benzes did not materialise overnight. The iconic East German Trabant was a two-stroke, flimsy, smoke-belching embarrassment of a car. It symbolised the utter failure of the Communist system to provide anything other than misery in people's lives.

  That, and East Berlin itself: crumbling buildings, many still pocked with bullet holes from World War II, dimly lit shops devoid of products, and stinking air filled with brown coal smoke.

  Traces of the wall that divided a city and two worlds remain. Actors don American and Soviet military uniforms and charge tourists to be photographed in front of the notorious Checkpoint Charlie. The souvenir stalls look scruffy. The crosses near where the wall stood are more poignant. Each one represents an East German killed while attempting to flee to the west. The first victim was Guenther Litfin, shot dead while attempting to flee in 1961. In 1962, border guards shot Peter Fechter and left him to bleed to death, close to Checkpoint Charlie. The last victim was 20-year-old Chris Gueffroy, in February 1989, killed only months before the wall fell.

  In the 28-year history of the wall, 245 people were killed attempting to escape, while 5075 escapes were successful. In the whole country, from 1948 to 1989, a total of 1347 people were killed by the East German border regime.

  Some good things from the past have been revived. The elegant Adlon Hotel, neglected in East German times, has been rebuilt. It's the hotel where the Princess of Tonga rented a suite, and Michael Jackson infamously dangled his baby from a balcony.

  Next door, the DZ bank building features a restaurant and meeting room full of extraordinary organic glass sculptures and curving steel and glass forms designed by architect Frank Gehry.

  Leading architects - Rem Koolhaas, I M Pei, David Chipperfield and more - have vied with each other to create exciting, dramatic new buildings. Many are government buildings and embassies, close to the River Spree on the east side. The new DB train station is a gleaming glass edifice that is functional and stylish. The scallop- shaped Sony Centre, at Potsdamer Platz, glows at night with changing coloured lights.

  One of the most dramatic buildings is the Reichstag, which was torched in the '30s by the Nazis (although they tried to pin the blame elsewhere) and damaged by Allied shells in 1945. British architect Lord Norman Foster gutted the building but kept the facade, and erected a huge glass dome on the roof. Visitors can walk around the dome and gaze down on the Bundestag, the parliament, below.

  I join Annette von Wesendonk, from the German Foreign Ministry, and New Zealand deputy head of mission Lisa Futshek for champagne in the dome restaurant.

  Futshek likes the buzz of living in Berlin and commutes by S-Bahn. Von Wesendonk goes by bike. She explains Berlin has several centres now: Mitte, full of shops and new buildings; the Brandenburg Gate; and Potsdamer Platz. The next day she takes me on a walking tour. One of the most evocative places is the Jewish Holocaust Memorial, by Peter Eisenman, where you walk amid 2700 grey concrete columns. It feels oppressive.

  Von Wesendonk then shows me an area undiscovered by tourists: the elegant square bordered on either side by a church, built in the 1800s. A saxophone player's plangent notes waft across the square as warmly clad Berliners stroll in the late-autumn sunlight. In the Gendarmenmarkt, I sample hot spiced gluehwein, and admire a beautifully stocked chocolate shop, cheese shop, and bakery.

  Museum Island contains all kinds of buildings, old and new. The Pergamon Museum is home to the Gates of Babylon, Greek and Roman statues, and a captivating exhibition of Islamic art.

  Another part of Berlin I don't have time to visit on this occasion is the Kaiser Wilhelm Memorial Church, a bombed shell left as a reminder of World War II, and the Kurfurstendamm, the former heart of West Berlin.

  After the wall came down, thousands left Berlin but many have returned, inspired by the city's encouragement of art, design and innovation in industry. However, the city has some surprises. It's a poor city by German standards, my hosts say, not like Stuttgart or Munich. There is still lots of empty space. The city is building more apartments in the city centre. Like most European cities, Berlin is a place to live. There is no deserted commercial centre, no sprawling suburbs. And, as in most European cities, everywhere is connected by a superb public transport system of rail, trams, and buses. Or you could bike. You don't need to own a car.

  Berlin used to have three airports. Tempelhof has closed. Tegel is provincial looking for a capital city (most international travellers arrive at Frankfurt or Munich). The third airport, Schoenefeld, will become the main airport.

  There is no doubt that Berlin is once again a major European city, and a centre for design and innovation. The political hub has shifted eastwards, but the German focus is Europe. Being committed to Europe is a major plank of German government policy.

  Beethoven's Ode to Joy, from 1824, with words by Schiller, sums it up: "Alle Menschen werden Brueder", "All men become brothers".

  Nearly two centuries later, the European dream of unity is a reality. It has come only after two world wars, millions of deaths, the devastation and division of the country, and the final collapse of tyrannical regimes.

  History is still very close here; it's a reminder that freedom has been bought at a tremendous price and that price should never be forgotten - but it's always worth celebrating. Berlin is celebrating in style.

  * David Killick is a senior writer for The Press. He travelled to Germany as a guest of the German federal government.