Thousands of people took to the streets in the German capital, Berlin, on Saturday to protest against rising rents, with other protests also staged in Cologne, Frankfurt and Munich.

DW's Jordan Wildon was at Berlin's well-known Alexanderplatz square as the protest got underway.

Organizers claimed 40,000 people attended the central event in Berlin, while the police announced only that the crowd numbered "far more than 10,000." The protesters marched through several city districts where people feel they are being priced out of their apartments.

"There's a massive sell-off happening in this city," Kreuzberg resident Paul Afred Kleinert said said at the event. According to the German author and translator, foreign real estate investors are especially keen on raising rents.

"Entire streets have been purchased by Japanese, Norwegian or American consortiums," Kleinert added.

Housing rents, particularly in Berlin, have doubled over the past decade, as Germany's booming job market continues to attract a large number of workers. This has put pressure on the housing market: Average rents in Berlin have pushed past €10 ($11.23) per square meter per month, according to a recent study by real estate group CBRE Berlin and German mortgage bank Berlin Hyp AG.

Read more: Germany's soaring housing prices spark calls for reform

Government intervention

Protesters are demanding the government step in and take control of the situation. On Saturday, they began gathering signatures for a petition that would see Berlin take over nearly 250,000 apartments from big rental companies. The move, coordinated by the Expropriate Deutsche Wohnen & Co. initiative, targets the biggest private rental player in Berlin, a company called Deutsche Wohnen. The firm owns 111,500 apartments, followed by Vonovia with 44,000. 

If the housing activists gather 20,000 signatures, Berlin's government would be required to consider the idea. If their response is not to the protesters' satisfaction, they have the option of gathering another 170,000 signatures by February 2020 to force a referendum on the issue.

The latest polls show a narrow majority of Berliners support the initiative.

In turn, Deutsche Wohnen said that selling their apartments to the city would not solve the crisis.

"Expropriation is creating a lot of emotions right now, but it won't create a single apartment," CEO Michael Zahn told the Associated Press news agency.

Additionally, such expropriation could cost the heavily-indebted city some €37 billion in compensation payments, according to the Berlin government. Housing activists have estimated the cost to be significantly lower.

Christian Pestalozza, a constitutional and public law professor at Berlin's Free University, believes the situation invokes Article 15 of the German constitution, or Basic Law, which provides for the "socialization" of "land, natural resources and means of production" by transferring it to public ownership.

Housing associations and developers have argued that expropriation won't solve the problem, saying the growing city urgently needs more housing — preferably in the form of new subsidized housing projects.

Activists, meanwhile, believe affordable rent is not only a necessity — they say it's central to the city's character.

"There needs to be some rules here for the game — it's a city, not just open land for people to do what they want," said Thomas McGath, a representative of Expropriate Deutsche Wohnen & Co., the group behind the campaign against rising rents. "It is not something that can be completely determined by the market."

The rental difference between privately and publicly owned houses in Germany has substantially increased in recent years, though they are still cheaper than in other major European capitals like Paris and London.

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'Class struggle'

Campaign organizers complain the government's measures to cool off the property market have failed.

"Many say this is a type of class struggle. Yes, that's what it is. But we did not start it. We are taking defensive measures against the class struggler from the top who has for years been fighting against tenants," campaign spokesman Rouzbeh Taheri told media ahead of the rally in Berlin.

Taheri believes it's necessary to cut these companies down to size, stripping them of the influence they wield on determining market prices.

"It is about sending a signal on which direction the city wants to go. And a signal to speculators — telling them that your capital is not safe in Berlin," Taheri said.

"We have to live somewhere. It's unacceptable for housing to become a commodity that is sold off, where the only concern is profit," said rental activist Daniel Diekmann.

Diekmann fully supports the referendum — he has been campaigning for housing rights for the last decade. He's lived on the same street in central Berlin for the last 16 years, and has witnessed how investors have sold off part of the 106 apartments in his building and modernized them, making way for luxury flats. Some 80 tenants have already moved away.

For Diekmann, it was time to do something. "The problem has made its way into mainstream society," he said.

"Having a place to live is a human right."

Smaller protests took place Saturday in other cities across Germany such as Munich, Cologne and Dresden. Protest organizers spoke of demonstrations in 19 cities with 55,000 participants. 

Read more: German real estate: Renters' woes are speculators' profits

dj, shs/jlw  (dpa, AP, AFP)

With additional reporting by Leonie von Hammerstein

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