For nearly thirty years, Seo Seung-ho has cleaned the windows of some of South Korea's tallest buildings. It's a reliable, well-paying job. There's just one problem: He's scared of heights.

Every day, starting from the 125th floor of the Lotte World Tower, Seo and his team of cleaners get into a special "gondola" and work their way down the building, to keep the tower gleaming.

Towering 555 meters (1,820 feet) over the Seoul skyline, the glass-and-steel spike is one of the tallest buildings in the world.

"I was afraid of heights, so I never thought I would do this job," Seo told AFP.

"But I had trouble making a living, and the job pays relatively well compared with other occupations, so I gathered my courage to start."

Weather is the biggest variable for Seo.

The gondola "is heavily influenced by the wind", he said, and there are times when "we experience winds we would never encounter in a lifetime".

One time, he said, the wind hit unexpectedly, causing the cleaners -- who are harnessed to the gondola -- to lose balance.

Another time, they had to wait an hour in the gondola, swinging in high winds, until the weather calmed enough for them to move to safety.

Between wind, rain, and snow, Seo and his team of seven barely manage to give the tower, which has some 42,000 windows, a full once-over every year.

"We can't clean every day because of the weather," said Seo.

"We usually start in April and work until the end of September or early October, which means we work about 65 to 70 days a year."

'Magnificent sight'

The tower's distinctive shape causes additional problems for the window cleaners.

"We prefer straight, square-shaped buildings, but the tower's slender cone shape makes it difficult to descend and clean," Seo said.

"There are many instances where the cage is pushed to the side and gets twisted as you go down."

His team use diatomaceous earth -- a powder made from the fossilized remains of tiny aquatic organisms -- to clean the windows, as it polishes the glass without scratching it and prevents complaints from pedestrians about getting splashed with soapy water.

"It's a great method, but when the wind blows, the rough particles sting our eyes," said Seo. "It's more difficult to work in the hot summer."

Even so, Seo says his job is "very rewarding as we are gifted with this magnificent sight" of Seoul from above.

The Lotte World Tower and the mall inside get nearly 50 million visitors annually, and the observation deck on the 123rd floor has become one of South Korea's most popular tourist attractions.

Cleaning the windows of the observation deck makes Seo feel like he's "helping a little bit" to show the city at its best to visitors.

"I live in Seoul, and I see the tower wherever I go," said Seo. "I feel proud, and I always will whenever I see the tower, even after I retire."