Notable at-risk residences include the Narkomfin building, an acclaimed example of Constructivist architecture and avant-garde interior design that is near the top of Unesco's endangered-buildings list. Designed in 1928 by the architect Moisei Ginzburg, the six-story concrete-block residence influenced Le Corbusier, who studied it during his visits to the Soviet Union. After decades of neglect, it is now a crumbling relic owned by the Moscow city government and under threat of demolition. The building is increasingly being eyed by developers because it sits in an area of particularly lucrative real estate near the U.S. embassy.

"There are a lot of buildings in Moscow that are simply not worth saving in their present state," says Nikolai Mitevska, an independent developer who has worked with several large Moscow-based property-development firms. He says that while he and other big builders respect the efforts of preservationists, the Narkomfin underscores how older architecture is often ill-suited for sustained use. "It has minimal amenities, and even some residents are modifying the outdated interiors already," he says. "Moscow is growing economically, and there is now a tremendous need for luxury property, and that simply needs to be addressed."

The three-story Melnikov House, in central Moscow, has long been considered a landmark of Soviet architecture. Designed by architect Konstantin Melnikov for his family between 1927 and 1929, its Constructivist form—made up of two interlocking cylinders with rhomboid windows—was widely celebrated across Europe. In the 1990s, there were attempts to restore the home, but it has been deteriorating ever since. Now officials have given permission to a developer to break ground for a nearby high-rise condo project, which preservationists say has affected the stability of the site. (Billionaire property developer Sergey Gordeev bought a share of the house two years ago, but his office says he plans to preserve the building.)

The Moscow Architecture Preservation Society, a group of architects, historians, and international heritage managers, is aggressively campaigning for urgent action to save important buildings. The group is petitioning local and federal governments while fostering ties with international organizations like the International Council on Monuments and Sites and the World Monuments Fund. Last year, preservationists from around the world gathered for the Heritage at Risk Conference, which called on Moscow's mayor and former Russian president Vladimir Putin to stem the demolitions and protect important architecture from being razed.

"Most people don't really understand that Moscow's architectural history is at stake here," says Marina Khrustalyova, director of the Moscow Architectural Preservation Society. She says that because property buyers aren't typically concerned with historically significant architecture, the struggle to preserve important structures is daunting.

"The same wealthy people wielding influence in politics and Russian industry will have to step in and join this fight," says John Stubbs, of the New York-based World Monuments Fund. "If not, it will leave a period of incredibly bold architectural ideas that were unique to Russia unprotected."