Taking an ironic poke at the mammoth-scale of the €552-million palace reconstruction, dozens of demonstrators set up an air-filled bouncy castle for children at the spot where the Stadtschloss once stood.
An international crowd with the motto "Cancel the Castle" hope they can convince the city to abandon the controversial architectural endeavour.
"The only good castle is a bouncy castle," protest organiser Joel Alas told The Local. "We want it to be known that people spoke out against the reconstruction of the palace."
The palace is slated to be rebuilt on Berlin's Museum Island, a UNESCO world heritage site in the heart of the city. Damaged in World War II, the original Prussian palace built in 1871 was demolished by East Germany's communist leaders in 1950. They opted to build the rubber-stamp parliament the Palace of the Republic, but that too has since been torn down.
Though it's exterior will look like the old palace, the interior will be modern and house some of the city's museums as the Humboldt Forum.
"This is a historical and cultural undertaking for Berlin and Germany," said Wilhelm von Boddien, president of the Berlin Palace Society, adding that he was confident the project would be realised in the coming years.
But many people question the idea of building a phony palace at such a high cost.
"Unfortunately for the kids enjoying themselves here today, they will be paying the bill for the palace in 50 years," Arno Paulus told the crowd of protesters.
And despite von Boddien's faith, there is talk that the incoming German government, a coalition between incumbent Chancellor Angela Merkel's Christian Democrats and the pro-business Free Democrats might delay the project for financial reasons.
Mariam Brandt, who was calling for the palace to "not be built in my name" on Saturday, said her main reason for being there was also financial.
"I think it's far too much money to spend on rebuilding a symbol of old power," she said. "There's no point."
Paulus also fears the final price tag.
"Most people in construction will tell you that a budget is by no means the final cost of the building,” he said. “This could be as much as 300 percent more expensive by the time the doors open to the public."
Protest organiser Alas, an Australian expatriate living in Berlin, would like to see grounds left as they currently are – a giant lawn bordered by the banks of the Spree River.
"You don't have to be German to know it's a stupid project," he said. "There are so many other ways to spend that money."
However, palace booster von Boddien believes the building will fill an important architectural gap in the heart of the capital.
"You can't always have parks in the middle of the city,” he said. “Berlin already has the massive Tiergarten in its centre. A city needs more than parks."
The awarding of the 40,000 square-metre palace's construction to an Italian architect has also caused trouble for the project. The federal regulators declared the contract given to Franco Stella was invalid. However, the Construction Ministry already plans to appeal the court's decision against Stella.
Reconstruction is slated to begin in the fall of 2010 and be completed by 2014.