– Time has stopped in the Golden Mile Complex. Inside the sprawling 1970s building, rows upon rows of travel agencies sit mostly empty, their employees staring into space. Stalls selling shoes, handbags, toothpaste and half-price stereo systems are illuminated in the gloom, while the smell of soap mixed with cheap perfume fills the air.

From the second floor, the strains of a solo karaoke singer can be heard, defiantly off-key, from one of several dimly lit Thai bars that are full of punters even in the middle of a weekday afternoon. The place does not just feel like it is from the past, but from another southeast Asian country entirely.

The building, once called a "vertical slum" by a Singaporean legislator, is a densely packed mix of residential and commercial units. Along with People's Park in Chinatown, which has been praised by the Dutch architect Rem Koolhaas, it is among a handful of Brutalist buildings that were built in a surge of architectural confidence after the country became independent in 1965. They are particularly adored by those who love concrete and bold colors.

Modernist buffs have started to fret that many of these Brutalist buildings will soon be gone. In February one of them, Pearl Bank, once the highest residential tower in Singapore, was sold for $544 million to CapitaLand, one of Asia's largest real estate developers.

The company plans to demolish the yellow horseshoe structure and build a high-rise residential tower of 800 flats in its place. Several of the other buildings — most of which are privately owned in a kind of cooperative system with hundreds of owners all having a stake — have started to prepare for sales, too.

In a place where public protest is frowned on by officials, anxious Singaporeans have been setting up well-mannered protest groups on Facebook to try to stop the demolition of Pearl Bank and other Brutalist structures, or have been writing impassioned opinion pieces in the state-owned media to try to influence CapitaLand, which is partly owned by the government.

The tiny city-state of 6 million people has always been cramped for space. Although it has grown in recent years through extensive land reclamation, land values remain eye-wateringly high.

According to government data, residential property prices were 44 percent higher in the first quarter of this year compared with the same period in 2009. The result is that many buildings have been torn down to pack more people into the same amount of land. In 2005, despite a large public outcry, the government tore down the much-loved National Library of Singapore to make way for a tunnel.

Although millennials were born long after these structures were erected, Brutalist buildings appeal to Singaporean youngsters partly because they are so different from the rest of the steel-and-glass city-state. The structures can feel subversive just because they still stubbornly exist. Weng Hin Ho, an architect, thinks they represent a time when there was "much more belief and conviction in doing things on our own," rather than relying on foreign multinationals to come in and build a city.