BERLIN (REUTERS).- Txus Parras, who has been squatting in the Tacheles building in downtown Berlin since the wall fell two decades ago, says he won't leave it without putting up a fight.

Tacheles is one of many forums for alternative culture in the German capital facing eviction from quirky historical properties which property developers want to transform into luxury flats, hotels and boutiques.

"Berlin is changing in a negative way, and it's not just about Tacheles, there is a force out there trying to destroy the this city's freedom," said 47-year old Spanish-born Parras at his atelier in the former bombed-out department store.

"I am part of the artist resistance," he said, sporting clothes died with symbols for love and peace, nose and lip piercings and lime-green felt earrings.

"I am going to make things very difficult for these people."

Artists from all over the world have been drawn to Berlin since the end of the Cold War, attracted by open spaces, low rents and the charms of a city Mayor Klaus Wowereit once described as "poor but sexy."

Parras, who has taught street art worldwide but keeps getting drawn back to Berlin, says Tacheles once housed 200 artists with 130 nationalities.

The five-storey building was occupied by artist squatters shortly after the fall of the Berlin Wall in 1989, and has since become a rabbit's warren of open ateliers, theatres and grungy bars. Walls are sprayed in layers of graffiti and plastered with posters, while a hint of marijuana lingers in the air.

"When you come in, it's a bit intimidating but I'm happy I did," said Italian tourist Fabrizio Biole, 33. "It's unique."

Tacheles -- meaning "straight talking" in Yiddish -- has become a top tourist site, yet it remains a symbol of Berlin's edginess and anarchic creativity.

PETITIONS
Tacheles is threatened with extinction, with its squatters locked in a drawn-out battle with property developers who want to build a massive residential and commercial complex on the prime real estate site in the heart of Berlin.

Visitors are asked to sign a petition stating "I support Tacheles" and posters protest the encroaching "grey men."

Tacheles is not alone. Just down the street, photography forum C/O Berlin is struggling to extend its lease in an ornate former post office which a new investor is keen to revamp.

Further along the Spree river, a sprawl of clubs and venues for alternative culture such as the Young African Art Market based in a former bus depot are staging lively demonstrations against plans to build offices for media companies there.

"The whole neighborhood is being changed," said Heinrich Buecker, 56, whose "anti-war Coop cafe" in the former East German district of Mitte serves as a meeting point for artists and organizers of Berlin's alternative scene.

"The alternative scene had its roots here," he said. "But now it is being pushed out to districts further out."

Many locals and visitors have rallied to the cause, while others protest that the buildings legally belong to new investors who are injecting much-needed capital into a city that has long teetered on the verge of bankruptcy.

"I'm not signing any petitions because western society and all our freedoms are founded on property rights," said Erik Higgins, an 18-year old student from Canada, as he perused artworks on sale in Tacheles.

"It's a beautiful place ... but you do wonder why they have to do something like this on land that is not theirs."

Given that Berlin is 60 billion euros in debt and has a high unemployment rate, it cannot afford to buy buildings like Tacheles or to push away investors, said Berlin's state secretary of culture Andre Schmitz.

CITY PLANNING
Tacheles' motley crew of creatives argue however they have been looking after the building for decades and are responsible for regenerating the entire area.

"We have been here for 20 years, taking care of this building and making it into the third most visited place in Berlin," said Parras, as tourists streamed past his studio along Oranienburger Street which now buzzes with restaurants and bars.

They say they offer a free space for culture, without charging any entry fee or receiving state subsidies -- unlike official cultural venues such as museums.

"The city should be thankful to us and support us," he added. "And if the city wants an alternative art culture, it should buy these buildings for us."

Organizers'' of Berlin's alternative culture scene foresee a drastic fall in tourists if it is forced to retreat into venues further out of the city center in the face of gentrification.

"Over 50 percent of tourists in Berlin are under 30 years old," said event organizer Lotar Kuepper at the Coop cafe.

"That means either city planning policy will be changed to relieve the pressure on the subculture, or the only real working industry in Berlin will collapse -- as will half the tourists."

Schmitz says he is relaxed about the alternative scene's future given how many empty spaces and buildings remain.

Critics say however that even if it reinvents itself elsewhere, it is the very the eclectic socio-cultural mix that forms Berlin's allure which is under threat, as gentrification pushes artists and people with lower incomes out of the center.

"It is a very free city, the social milieus are porous -- New York was like this in the 70s and 80s, very relaxed, but it became expensive, clean and orderly," said C/O spokesman Mirko Novak, sitting in a half renovated room crammed with books.

"Berlin just needs to be careful if it wants to keep its image of an open and creative city."