“The way I see it, they don’t bother, they protect,” Jay said, as rain began to drum on the plastic tarp covering the outdoor kitchen, where he was helping to serve a communal breakfast of donated bagels and peanut butter. “We have never had a problem with the police.”

Likewise, the Frankfurt police have never had a beef with the protesters, said Manfred Vonhausen, a police spokesman. “The people there have been totally calm,” he said.

The activists chose the site next to the E.C.B. to protest what they consider the bank’s aloofness from the democratic process and the austerity it is helping to impose on indebted countries like Greece. But the protesters do not seem to be very aware of the central bank’s policy actions, like its rate cut last week.

Leftist movements have a long history in Europe, and the German police are used to dealing with neo-Nazis, extreme-left “Autonomen” and other groups with much more of a hang for violence than the Frankfurt campers, who do not even rate a permanent police presence.

“The U.S.A. is not as used as the Europeans to dealing with these movements,” said a 50-year-old Occupy Frankfurt resident who would identify himself only as Uwe. He was managing an information stand fashioned from plastic tarps and wooden freight pallets, where passers-by could pick up leaflets and perhaps make a donation to help pay for portable toilets and other camp infrastructure. The protesters have been careful not to obstruct heavily traveled walkways that lead through the park from a nearby streetcar stop.

A few minutes later, Uwe, wearing a rumpled red overcoat, assumed the role of tour guide for a group of students in their last year of secondary school. He lit a hand-rolled cigarette as the students gathered around him in a semicircle, then described how the activists had rigged up a computer server in one of the tents.

“Very interesting,” said Nikolay Schiljahin, one of the students. A classmate, Sandro Kaufmann, said he agreed with protesters that “banks have too much power” but he was not quite ready to join the cause. “They need to form their arguments better,” Mr. Kaufmann said.