Saint Isaac's cathedral, center, stands illuminated past the Blagoveschensky flap bridge in St. Petersburg, Russia. (Andrey Rudakov/Bloomberg)

From a deep second-floor window of a Russian noble’s old mansion on the west side of the square, you look straight on at the dark, looming majesty of St. Isaac’s Cathedral, stolid under its huge golden domes. Beyond, at a slight angle, lies the fabled Hotel Astoria, a Style Moderne red-brown northern stone masterpiece from 1912. To the right, past the statue of Nicholas I on a rearing horse and across the Blue Bridge, your eye catches the imperious Mariinsky Palace, flying the gallant ­anchor-and-grappling-hook flag of St. Petersburg. To the left lies the spring-green Alexander Garden, and past it flows the broad Neva River.

You are in the Red Hall of what is now the Institute of Art History, a magnificent embodiment of the 19th century’s finest decorative arts. And if you’re a developer, you might find yourself thinking: Does a square that is so historically appealing and beautifully intact really need this much culture? Couldn’t the scholars who study here go somewhere else so that this handsome old marble house could be put to more, shall we say, lucrative use?

That, at least, is what Tatyana Klyavina worries about. Until June 18, she was the director here, but she made such a fuss over what she believes to be plans to destroy her institute, and to turn the mansion into a hotel or banquet hall or addition to the new Gazprom building that towers right behind it, that finally the Ministry of Culture fired her.

That, of course, did little to reassure the institute’s up-in-arms employees that her fears were groundless.

Developers and preservationists tussle the whole world over, but feelings run especially high in the city founded by Peter the Great as Russia’s window to Europe. In a country studded with concrete apartment houses, St. Petersburg is a riverside jewel — once dreary and dusty after decades of Soviet neglect but now spiffed up again. Yet with all that spiffing comes a dizzying increase in property values. Which leads Klyavina and others to worry that St. Petersburg won’t survive its own real estate potential.

Add to that a government and bureaucracy that are notoriously corrupt and almost universally disbelieved. So when the Ministry of Culture announces that of course it has no plans to eject the institute and make some money off a new use for the mansion — well, that would seem to spell trouble.

“The minister says that, his deputies say that,” said Klyavina, who left after 21 years. “But what they actually do does not provide any grounds to trust them.”

Fears of a broader assault on St. Petersburg’s legacy are brewing. This month, Russia prepared a draft document for the United Nations Educational, Scientific and Cultural Organization’s world heritage conference that looked like the beginning of an attempt to remove great swaths of protected historic Petersburg property from the organization’s list. Definitions became much more vague, and preservationists were in an uproar.

“It’s a fight for property for investors and developers,” said Sergei Gorbatenko, who runs the St. Petersburg branch of the International Council on Monuments and Sites. “A fight for money — that’s the root. And, of course, corruption. Corruption penetrates the whole question.”

The great czar-era countryside palaces are not threatened, but lesser known historic sites are in real danger, Gorbatenko said — the 18th-century landscaping on the grounds of the former Alexander Dacha at Pavlovsk, for example, or the nearby Samoilova Dacha.

The foreign ministry, which represents Russia at UNESCO, said in a statement that the document is still only a draft and that no action is imminent. But there was enough of an outcry in St. Petersburg that the city has set up a special working group to thrash out the question. The problem, from Gorbatenko’s point of view, is that most of its members are city bureaucrats with no particular expertise in architecture, history or preservation.

“UNESCO designation creates a moral background and an ethical background,” he said. Removing properties from the list, even minor ones, sets a very bad precedent, he said, because it lets developers get a foot in the door. What, he wondered, will they ask for next time around?

(Russia has already moved to exclude certain parts of the western Caucasus region from UNESCO designation as it prepares for the 2014 Winter Olympics with a frenzy of construction.)

On Thursday, Prime Minister Dmitry Medvedev, a St. Petersburg native, called for reform of the Russian Academy of Sciences, saying, among other things, that scientists should stop having to worry about managing property. Most of the huge holdings of the academy are in Soviet-era satellite towns, but there are enough old and famous institutes here, and in Moscow, to make preservationists wonder whether this, too, is a land-grab masquerading as reform.

Last winter, the National Library, in a pastel-blue classical building from 1835 just off Nevsky Prospect, the city’s main street, came under pressure.

Quietly, the word came down from somewhere high up in the government that it might make sense to move the collection elsewhere, said Ilona Svetlikova, who works at the Institute of Art History.

That, said Klyavina, her former boss, is how it started at the institute on St. Isaac’s Square. The staff was reduced, and then came suggestions that their home was too large. There was a proposal to make the institute, which still employs about 100, a subsidiary of a different, much smaller cultural organization.

“There have been several attempts to take this building away from us, which means, in fact, closing the institute,” she said.

Not at all, said Yevgeny Velikanov, the ministry’s press secretary. “The Ministry of Culture does not have any plans for the reorganization of the institute; the issue of the institute’s liquidation has never been on the agenda and has never been discussed,” he said. “The institute will not be liquidated. There is no talk about the redistribution of property.”

Marina Kornakova, who quit her job at the institute in April, isn’t buying it. “It’s the murder of the institution,” she said.

Count Valentin Zubov founded the institute in his own home in 1912, and after the Bolshevik Revolution, he deeded it to the government before it could be seized from him. He continued as director, living in an apartment in the back, until he left the country in 1925. Today, it is one of the preeminent cultural institutions in St. Petersburg, boasting a library of half a million volumes.

For the past six years, it has been undergoing a meticulous renovation, but Culture Ministry officials have complained about the quality of the work and said that it might need to be redone. (Water damage is in fact visible in both a back stairway and on one wall of the astonishing Green Hall, which is a vibrant malachite shade of the color.) Klyavina’s allies on the staff believe another renovation will be used as an excuse to expel the institute and incidentally provide the opportunity for officials to line their pockets a bit more.

The institute survived the nearly 900-day siege of the city during World War II, and it survived the advent and collapse of Soviet Communism. But now, Klyavina says, it faces the greatest threat in its history.

“Our problem,” she said, “is that our institute is located in this beautiful building. And our building is located in the center of St. Petersburg.”