Keith Duggan World Cup LetterAmong the 20,000 Dutch fans making fun in downtown Leipzig on Saturday night was a man dressed in an entirely orange tuxedo. Many of his countrymen had gone to enormous trouble to concoct outlandish costumes in the national colour but this man was the runaway winner and he hammed it up, solemnly walking through Augustus Platz as though surrounded by chandeliers and champagne cocktails instead of thousands of boozed up Netherlanders singing Queen's We are the Champions" over and over.

The Dutch consumed beer at an astonishing volume that night and the barkeepers in Leipzig were perfectly happy to oblige them. Leipzig's night life is concentrated in the bistros and cafés around the old market area in the centre of town. Once you left that district, walking up past the sumptuous Opera house and across the Georgiring road and tram line, you could hear the Dutch in the distance, bellowing and cheerful and happily off-key. And when the sound of their singing faded, it became clear Leipzig at nightfall is an overwhelmingly quiet city.

As a tall, raffish Dutch youth named Johann remarked breezily on the tram the next morning, "It has not even been 20 years." He was talking about the reunification of Germany and his remark was provoked by the sight of a vast building, some five stories high and 16 windows long, boarded and chained and graffiti-sprayed, bleakly and permanently closed off.

We wondered at its demise: it had obviously been an important place once upon a time.

There are buildings like this all over Leipzig, in the no-frills, functional architectural style of communist Europe and now falling into ruination amid the splendidly restored 18th- and 19th-century state houses and the international fashion and coffee houses.

Leipzig's combination of shuttered buildings and spanking new business and cultural ventures leaves visitors with the unavoidable impression of a city coming into bloom again.

Still, it is impossible not to wonder at what life was life "before". On the long and jubilant orange march to the stadium on Sunday morning, local people enjoyed the sight, peering out among flowerpots on wrought iron balconies and standing in the shaded doorways of their shops.

Frau Deuther works in her son-in-law's new bookshop at weekends and she agreed the sight of noisy, raucous football fans crowding Ebert Strabe was a novelty. She was born in 1939 and for locals of her generation, the carefree exhibitionism brought on by this World Cup match remains little short of a miracle. She spent most of her working life in Chemnitz, an hour south of Leipzig but returned to the city of her birth when communism fell in 1989.

Asked about the main difference between then and now she said, "It is all so clean now. Then, everything was destroyed."

The most notable example of this is the 15th-century Thomaskirche. Johann Bach was cantor there in the mid 1700s but it was also where Martin Luther first preached the Reformation in Leipzig. It was used as a munitions store by Napoleon's troops in the early 19th century and Bach's grave was moved to the altar there in the first years of the East German state. It would become a poor resting place for the great composer, falling into ruination and neglect until EU funding facilitated a restoration after 1990.

About five minutes' walk from Thomaskirche, along the leafy Dittrichring, is the building where the Stasi headquarters were located. The place was turned into a museum just two years after the end of East Germany. For 40 years a house of paranoia and fear, it now showcases all the trappings of Iron Curtain police intelligence, from secret cameras to the comical range of fake moustaches and ears and "Arab" costumes. But it retains a powerful, disquieting atmosphere.

Because the Stasi believed everybody was a suspect, some six miles of personal files were found in the building after 1992. Apartments were obsessively bugged and searched, neighbours encouraged to snitch and practically every citizen was photographed. There are entire walls of these black and white shots from the 1960s of 1970s, of young people on bicycles, old women outside churches. Decades of this state-sponsored paranoia must have had a profound effect on Leipzig citizens old enough to remember.

As I stood with the museum curator looking out what had been the veiled window of Lieut Hummitzsch's office, watching the football fans striding past, it seemed appropriate to remark that times had changed.

After winning the match 1-0, the Dutch resumed their appreciation of Freddy Mercury. It was more interesting to gather with the few hundred Serbians congregated outside the Nikolaischule café, another of these preposterously beautiful Germanic buildings, now an alehouse.

They had brought their own brass band and sang dirges and upbeat marching songs until the early morning. Sasa Markovic was born in Belgrade but grew up in Germany. He reckoned any fan that had made it from the old country was almost certainly "mafiosa". There is no other way they could have afforded it.

Asked about the independence of Montenegro, Sasa shrugged in exasperation. "They wait until they get all the good things - money, buildings, everything, now they leave. Serbia is like the mother, Montenegro the son."

The heart of the city was still lit with the bright orange shirts, singing, eating and drinking. You had to wonder if there wasn't one or two believers of the old regime seeing in this parade of decadence a shocking manifestation of all their worst fears.