Berlin has faced some astonishing transformations. The 20th century has been marked by periods of repression, resistance and the struggle for self- expression, punctuated by bouts of furious economic activity and cultural innovation. The city has wrestled with defeat in two world wars, the fragile 14-year democracy of the Weimar Republic, followed by the horrors of the Third Reich. Added to this, a brutal Soviet invasion, and devastating Allied bombing at the end of the war, destroyed 65 per cent of the city’s buildings. The construction of the Wall in 1961 left Berlin an isolated outpost of capitalist democracy in the West, a communist colony in the East.

Five years ago the collapse of Communism brought optimism together with the tricky logistical and psychological problems of integrating two social systems which had developed at different speeds and in different directions. The Federal government plans to spend Pounds 850 billion on construction projects in eastern Germany, with Pounds 250 million earmarked for Norman Foster’s scheme to refurbish the Reichstag as the future seat of government. Berlin is a newly vibrant city with a fascinating political and cultural history to explore. There are more than 125 major museums in the city.

The economic and political disaster of the Weimar Republic, from 1919-1933, was a period of astonishing creativity for Berlin, a uniquely fertile phase in the history of German cinema and design. The UFA Studio in Babelsberg, on the edge of Potsdam, produced memorable silents including The Cabinet of Doctor Caligari, The Golem and Metropolis, followed by Dr Mabuse, M, The Blue Angel and other early talkies.

Under the Nazis, Goebbels here oversaw production of schmaltzy escapist trash alongside newsreels and poisonous anti-Semitic propaganda such as Jud Suess.

With the Communist takeover, the renamed DEFA Studio became the centre of feature film-making in the DDR. It has now been turned into a Hollywood-like “Studio Experience,” with an inept attempt to recreate the atmosphere of the early films. There is also a stunt show, a visit to the props and costume store and a re-creation of a Berlin street, more for Spielberg and Schwarzenegger fans than serious film buffs.

Within weeks of seizing total power, Hitler suppressed the activities of the Bauhaus group of artists, architects and craftsmen, then working in a disused telephone factory in the Steglitz district. The Bauhaus Archive, south of the Tiergarten, preserves the legacy of Walter Gropius, Mies van der Rohe, Marcel Breuer and others, with a splendid collection of architects’ models, furniture and tableware, which underlines their influence on everyday products and the built environment.

There are few physical reminders of the Third Reich in contemporary Berlin. The Olympic Stadium still stands impressively on the edge of Charlottenburg and Goering’s lumpy Air Ministry miraculously escaped destruction in Wilhelmstrasse. This was one of a series of buildings including Hitler’s Reichs Chancellery which formed the power centre of the Nazi regime. The area is more accessible now the Wall is down.

The repression of this period has not been forgotten in the stark Topography of Terror exhibition in the cellars of the Gestapo headquarters. It illustrates the structure of the SS and the Gestapo and their central role in the government system of the Third Reich. Conditions in the death camps are harrowingly recorded and tribute paid to those who were persecuted.

The depth of resistance to the National Socialists is often under-estimated and was tragically ignored by the Allies during the war. A small museum in the former General Staff building of the Third Reich, in the aptly named Stauffenbergstrasse, is a touching memorial to the many who lost or risked their lives. A plaque marks where von Stauffenberg and his co-conspirators were shot after the assassination attempt on Hitler in July 1944.

It is an irony of history that Erich Honecker spent 12 years in a concentration camp, yet, as Communist Party Secretary of the DDR from l971-1989, went on to maintain and develop an equally pervasive system of repression. Romania apart, Berlin was the most heavily policed state in Eastern Europe, a not-so-soft version of the Third Reich. One million spies and informers worked for the State Security Police, the Stasi, in a population of 16 million. The full extent of its hold on the country was only fully revealed when its complex of buildings in Lichtenberg was ransacked by the people of Berlin on January 15, 1990.

A museum has opened in the former Stasi headquarters in Ruschestrasse to remember those who “fell victim to the DDR”. The most interesting section is quaintly referred to as “a collection of Stasi knick-knacks”. There are examples of bugging devices, including hidden cameras, one in a watering can, another in a bird’s feeding box. A Trabant door packed with a huge infra-red camera is also on display alongside other sinister spy technology. Visitors can wander round the office and apartment of Erich Mielke, now over 80 years old and locked away in Moabit jail, who controlled the operations of the Stasi from 1957 to l989.

Security in the DDR was dominated by the desire to prevent its citizens from leaving the country. Astonishingly few traces of the Wall are left, apart from the patrol roads which have been appropriated as convenient cycle tracks by suburban Berliners. The remaining installations at Checkpoint Charlie and the Haus am Checkpoint Charlie museum recreate the atmosphere of the Cold War.

The Haus am Checkpoint Charlie offers a striking record of the ingenuity of escapers. There is the Isetta bubble car used to conceal 18 escapees before it was discovered and the home-made flying machine powered by a Trabant engine which transported a 24-year-old student from Czechoslovakia in 1984.

In the past five years eastern Berlin has witnessed an upsurge of the kind of avant-garde and satirical art which the Stasi did everything to snuff out. The East Side Gallery is a 1.2km stretch of the wall running along Muehlenstrasse between the Hauptbahnhof and the Oberbaum bridge in Friedrichshain. More than 100 artists from 2l countries have been invited to paint murals on the bare concrete in what could be the world’s biggest open air art gallery. The most striking of them shows Honecker and Breshnev kissing passionately in a fatal embrace.

“Wo ist KapitAn Nemo?” is not the first thing you would expect to read on a giant mural on the side of a derelict department store in Oranienburgerstrasse near the old Jewish Quarter, on the edge of Prenzlauer Berg. Tacheles is an arts centre set up in 1990 by 50 alternative artists. They come here to paint and sculpt, display their work and produce exotic exhibits for the huge outdoor sculpture park.

A Dance Between Flames by Anton Gill, published by John Murray, gives a detailed account of Berlin’s history between the wars. Berlin, the Biography of a City by Anthony Read and David Fisher, published by Pimlico Press and the new Rough Guide to Berlin, from Penguin, are also invaluable.

The German Tourist Board and Lufthansa enabled Stephen Thomas to research this article.