T HE MOSQUE will be left standing. It is perched on top of a hill not far from Itaewon station, at the foot of Namsan, the mountain that towers over central Seoul. Its forecourt offers a commanding view of a jumble of low-rise houses set along winding streets, which give into ever narrower lanes garlanded with precarious-looking power cables. At night the area becomes a glittering sea of streetlights, with neon crosses marking its many churches. But the view from the hill may soon change beyond recognition. If current plans are realised, the tiny alleys and houses will make way for a regular grid of streets filled with the sort of high-rise apartment blocks in which two-thirds of South Koreans live.

The view is not the only thing that would change. The neighbourhood around the mosque, which straddles the districts of Bogwang-dong and Hannam-dong, is Seoul’s most diverse, an oddity in a country with few foreign residents, next to no ethnic diversity and strong social conformity. In addition to a tiny Muslim community, the area is home to a vibrant gay scene, a host of foreign restaurants and the remains of a shabby red-light district that used to cater to soldiers from a nearby American army base. (Most of its personnel have moved to a site outside the city.) Little of that would remain if the redevelopment went ahead, reckons Minsuk Cho, an architect who has built his new office nearby.

The planned redevelopment has deadened the area in some ways, while enlivening it in others. Over the past few years, many residents have left; beyond the main streets, buildings stand desolate and crumbling. But cheap rents in the quasi-condemned buildings have attracted a host of young South Koreans who have set up bars, restaurants, shops and art galleries, and rub along happily with older inhabitants. Eun-me Ahn, a dancer who has lived on the hill for six years, particularly likes the fact that everyone knows everybody else, despite their diverse backgrounds. “My neighbour has been here for 30 years,” she says, “and everyone gets along.” Little of that will survive if the area is razed as planned, she reckons. “I guess we’ll all just have to go somewhere else,” she says. “It’s a bit sad, because the memory of what it used to be like will disappear.”

This being Seoul, the memory Ms Ahn wishes to preserve is quite recent. The layout of the area dates to the 1960s and 1970s, when South Korea was rapidly urbanising. It started out as a “moon village”, one of the many shantytowns that sprang up on the city’s hills after the end of the Korean war, so called because the steep terrain did at least provide a good view of the moon. Over time, these settlements acquired paved roads and brick-and-mortar houses, eventually turning into lively working-class neighbourhoods.

The mosque was built in 1976, mostly as a gesture to attract engineers and investors from the Arab world. Saudi Arabia paid for most of it. It has drawn immigrants from Muslim countries to the area, says Muhammad Yun, a 66-year-old Korean who converted to Islam after living in Saudi Arabia in the 1980s and now shows visitors round the mosque. “People around here are welcoming to immigrants,” says Usman Khan, who moved to Seoul from Pakistan 20 years ago and has become a citizen. He works in a small supermarket near the mosque, while also running a restaurant in another part of town. Mr Yun says that many of the area’s immigrants have been vocal in their opposition to its redevelopment, displaying red flags outside their shops in protest. Mr Khan, however, says he is relaxed about the changes. “I’ve done so many different things in my life. I’ll adapt.”

The destruction of the neighbourhood would not be unusual in modern Seoul, which has been characterised by rapid and frequently brutal changes. Japanese colonialists redeveloped much of the city during their occupation from 1910 to 1945. The city, old and new, was almost completely destroyed during the Korean war. Afterwards, the pressing need to accommodate new residents took precedence over preserving existing structures or honouring the city’s historical fabric.

Although the current appearance of the neighbourhood is a great improvement on the unpaved roads and shacks of the past, the little houses with their cramped rooms and rusty water pipes are no longer seen as fit for purpose in what has become a rich country. Since the area was earmarked for redevelopment, its decline has been accelerated by neglect. “Most of the houses are now owned by investors who are just waiting for the bulldozers to move in,” says Choi Tae-chul, a local estate agent.

Because they are expecting demolition, most landlords have given up making even basic repairs. The house which Ms Ahn rents had water pouring through the ceiling when she moved in; she fixed it up herself. But for many residents, that is not an option. Park Cheong-rye, an 80-year-old woman in a colourful cardigan who is waiting outside a salon to get her hair done, says she understands that the area is in need of improvement. But she would prefer a less extreme approach than knocking it all down. She has sold her house to an investor, but continues to live in it as a tenant: “I don’t know where else I could go.”

A short walk up the road, Bae Heung-kwon, who is sitting in the back of an open lorry, demurs. “All the residents want redevelopment because that way we can take advantage of the rising property prices by selling to outside investors,” says the 80-year-old laundry-owner. He grumbles about an edict from Park Won-soon, the mayor, which has limited the height of the proposed apartment blocks to 22 storeys as a condition for their approval. He feels that the mayor’s “European ideas” about the urban environment are short-changing residents. “We wanted 40 storeys, because that way the land would be worth more.”

The mayor’s ideas actually come from a Korean architect. In 2014 Mr Park created the position of “city architect” for Seoul, aiming to break the hold of speculators and developers on urban planning and to make sure new housing projects take more account of Seoul’s heritage and terrain. Seung H-Sang, the first person to do the job, believes that decades of rapid development have cost the city its identity. “We have all these landmark high-rises but they have no relationship to one another,” he says. “New buildings should take account of what’s already there and also of what used to be there.” His first move after taking office was to put a moratorium on projects he thought violated this principle, including the original development plan for Hannam-dong.

Mr Seung dreams of a Seoul in which people can walk unhindered from A to B . To anyone trying to get around the city on foot today, the audacity of that plan quickly becomes clear. Neighbourhoods are often sundered by motorways, canals and railway tracks. Pedestrians who do not know their way can find themselves stranded, far from the right overpass or underpass.

In contrast, the lanes of Hannam and Bogwang are an invitation to linger and explore. Despite their steepness, they are well served by a tiny neighbourhood bus. The area seems suited to Mr Seung’s “acupuncture” style of gradual, small-scale regeneration, which Mr Park, the mayor, espouses.

Mr Seung says that everyone must be involved in the planning process to make a city liveable. He criticises the views of the majority: “Koreans think of houses as assets to buy and sell, not as places to live. During the years of the military dictatorship we were told that making money equals happiness, and too many of us still believe that.” Mr Seung sees the preference for living in apartment blocks as a remnant of the authoritarian era and therefore something to be overcome. For now, he wants to focus on reducing the number of apartment blocks built. “But eventually, all those ugly blocks should be torn down.” Large-scale demolition, it seems, is something all Seoulites can agree on, whatever their taste in architecture.