Banpo Xi apartment complex and other apartments are seen in Seoul, South Korea. Banpo Xi is one of the most expensive apartment complexes in South Korea. (Shin Woong-jae/For The Washington Post)

South Korea is a nation covered by apartments, so much so that from above, it resembles a coast-to-coast line of dominoes. Apartment buildings snake around mountains and form jarring clusters in the countryside. In cities, they align in grids that stretch for miles.

Apartment buildings first sprouted decades ago as a way to accommodate South Korea’s booming middle class, and they were the picture of a nation in rapid ascent.

But the most remarkable thing about them isn’t the national transformation they heralded, urban design experts say: It’s their staying power.

South Korea today is dominated by tech giants, its streets filled with neon lights, coffee shops and barbecue joints. But despite its first-world status, it hasn’t seen a new demand for townhouses, city-center living or artsy warehouse districts. Rather, people still prefer to live in apartments that look nearly unchanged from the boom years — units built by Hyundai or Samsung or Lotte, in buildings 15 to 30 stories tall.

Although the country’s real-estate market has slowed, apartments form the backbone of preplanned cities under construction, such as Dongtan, where 100 complexes — for 310,000 people — are being built in a loose ring around a golf course. Apartment buildings are also pushing into some of Seoul’s classic neighborhoods. A few mid-size cities have mega-towers, 60-some stories high.

Some South Koreans say that the apartments have become a symbol of success and that moves into bigger units serve as milestones in their lives. After college: first apartment. After marriage: a bigger apartment. As children grow: a similar apartment in a better school district. The average Korean moves every five years, a steady vertical migration, and about 60 percent live in apartments, up from 1 percent 40 years ago, according to a recent book, “Apartment,” written by Park Cheol-soo, a professor at the University of Seoul.

‘They’re just stacked up’

Most Korean apartments are rectangular, and few have balconies. Their biggest windows tend to face south or southeast, offering the most sunlight. Most buildings have construction company logos and unit numbers stamped on the sides. They do not rise from the street with businesses in the bottom floor or two. Rather, they’re built in complexes that are strictly residential, with one or two guarded entrances. Only residents or approved visitors may enter. Modern facilities have playgrounds or fitness centers for residents.

Koreans aren’t blind to the downside of such a style. The walled complexes close off large plots of land to the public, and the apartments themselves cut the nation into millions of impersonal cells. At one complex in Jamsil, on the outskirts of Seoul, 19,000 people live in a single city block containing 72 high-rises.

“There isn’t much design inspiration. They’re just stacked up,” said Park In-seok, an architecture professor at Myongji University. He described a paradox in which the apartments are mocked for their appearance but coveted for their convenience.

“Almost everybody hates the apartment,” Park said. “But everybody wants to live in one.”

South Korean society emphasizes the family, not the community, and analysts say the apartments reflect that: The individual units look much nicer than the buildings they’re in. Particularly in apartments built since the 1990s, the interiors are comfortable, with wooden floors and stainless-steel kitchens. Outside maintenance is provided, and families can focus on their own small spaces.

“It is convenient,” said Kim Sung-jin, an employee at Dell who has lived in three different apartment buildings in the past 17 years. “Plus you have a security guard. There’s a parking space for you. There’s a school nearby.”

The apartments, initially, were a means to hold South Korea together during its growth after the Korean War. Government officials sometimes said that if people became dissatisfied with their living situations, they’d be likelier to protest against the government, at the time controlled by military leaders. The first apartment buildings, South Korea’s national housing developer said in the 1960s, would “contribute to the aesthetics of the capital city” and serve as a useful propaganda tool — showing North Korea the affluence of the South.

Best seen from a distance

Many of South Korea’s early apartment designers studied in the United States and were perhaps influenced by the boxy look of stand-alone suburban homes, some experts say. But they acknowledge that South Korea’s apartments have a distinctly communist feel and resemble the buildings seen in some parts of Moscow.

South Korean construction companies try to differentiate their apartment buildings — each firm uses its brand name, like the IPark, the Castle — but experts admit there’s little difference between them.

An annual contest is held to pick the best apartment complex constructed within the previous calendar year. Ten urban designers and architects tour the country by bus, inspecting applicants’ buildings and interviewing residents.

One judge says that copycatting is rampant and that modest innovations by one developer are soon adopted by others. Fitness centers. Artificial streams. Underground parking. Ahn Kun-hyuck, the lead panelist, said the contest in some years is “very hard to judge.”

If the apartments have a beauty, it’s best seen from afar — a scale that recognizes their utility and militant geometry. Kim, the Dell employee, is an amateur photographer, and he sometimes darts out of work at dusk and heads to mountain ridges or scenic lookout points. The sky is orange, the massive Han River shimmers, and the apartment buildings catch just the right light.

But Kim said his best photos actually come minutes later, when the sun sets.

With nightscapes, “you only see beautiful lights,” he said. “You don’t see the ugly things.”

Yoonjung Seo contributed to this report.