Thousands of Roman Catholics and supporters marched in Bucharest on Sunday to protest against the construction of a high-rise building they say threatens to damage a 19th century cathedral nearby.
Police said some 6,000 people took part in the protest, held after a local court in June lifted an injunction to freeze construction following concerns from the Vatican, members of the European Parliament and US State Department.
Activists say the case illustrates the pitfalls of a free-for-all real estate boom in Romania, a new European Union member, that endangers historical and architectural landmarks of Bucharest, already badly scarred by communist-era demolitions.
Many say corruption and lack of administrative oversight may overrun neighbourhoods of modernist villas dating back to the early 20th century that earned the Romanian capital the name of "Little Paris".
Chanting and holding signs that read "The city must belong to its citizens, not to the real estate mafia" and "Bucharest is dying, why aren't you in pain?", the protesters collected signatures for a petition to stop works.
The Roman Catholic church in Bucharest accuses the developer of the multi-million-euro project to build the "Cathedral Plaza" office building of failing to obtain appropriate permits before starting construction in 2006.
"We are fighting for old, historical spaces, threatened by buildings ... and many threatening to ruin the life around them," said Niculae Radulescu-Dobrogea, head of a local NGO.
"I am hoping this mammoth which doesn't belong here is demolished."
The developers say the cathedral is not at risk and their paperwork is in order, blaming Romania's weak judiciary for stopping construction and accusing church authorities of lack of cooperation.
"For the past three years the bishop refuses to let us bring experts into the cathedral to assess risks," said Daiana Voicu, an official at Willbrook Management International, a real estate developer that oversees the project.
Since Romania joined the EU in 2007, real estate investment has been a key engine of growth but developers' projects are marred by red tape and unresolved property ownership issues that date back to the pre-1989 communist regime.