Lotte World Tower

South Korea's tallest building at 555 m and 123 floors, with a sleek tapering, brush-like form.

The tower was designed by the American architecture firm Kohn Pedersen Fox. Its smooth shape, which narrows gently as it rises, was inspired by traditional Korean pottery and by a calligraphy brush. Inside are shops, offices, homes, a hotel and, at the very top, an observatory called Seoul Sky, where a glass floor lets visitors stand high above the city with nothing but glass beneath their feet.

How it was built

Planning and site preparation took 13 years before the government gave final approval in 2010. The base of the tower is a giant concrete mat, about the size of 80 percent of a football pitch. To make it, 5,300 concrete mixer trucks poured 80,000 tonnes of extra-strong concrete in 32 hours without stopping. The tower was designed to stand up to wind gusts of 80 metres per second. In 2016 a steel diagrid crown, a criss-cross lattice of steel shaped like a lantern, was finished on top, covering floors 107 to 123.

Seoul Sky observatory

Seoul Sky fills the top seven floors, from 117 to 123. On the 118th floor is the Sky Deck, with a glass floor that was recorded as the highest glass-floored observation deck in the world when the tower opened. Visitors ride up from the basement in the Sky Shuttle, a double-decker lift that reaches the top in about one minute; it set records for speed and for the longest distance travelled by a double-deck lift. On clear days you can see as far as the Yellow Sea.

Why it's famous

Lotte World Tower is the tallest building among the OECD countries, a large group of mostly wealthy nations, and today it is the sixth-tallest building in the world. Its slim silhouette can be seen from much of Seoul, and its outside is covered in LED lights that can show pictures and words: on New Year's Eve 2015 it lit up with the number 2016. For daring visitors there is a Sky Bridge Tour on the roof, 541 metres up.

On the globe

The model shows Seoul's tallest skyscraper with its sleek, tapering, brush-like form rising to a narrow top. Zoom in to see how the tower slims down as it climbs.