Sebitseom

Where it sits. Sebitseom is a group of artificial islands moored in the Han River off Banpo Hangang Park, on the southern bank in Seocho District, just downstream of Banpo Bridge. The name means three lights; the complex is officially branded Some Sevit. It is joined to the riverside park by a short footbridge, and from the deck the view runs upstream past the bridge decks toward Namsan and the tower on the northern skyline.

The story behind it. The idea came from a Seoul resident, Kim Eun-sung, who proposed floating structures on the Han in a city suggestion scheme in 2006. The city procured them under a build-transfer-operate concession, and they opened in 2011 after a difficult construction and a period of political controversy over cost. They are described as the first floating buildings of their kind erected on buoyancy structures that rise and fall with the river rather than on piles driven into the bed — a meaningful distinction on a river whose level is managed by upstream dams and can move considerably during the summer monsoon. There are three islands: Gavit, the largest, shaped as an opening flower bud and holding a convention hall; Chavit, conceived as a seed; and Solvit, a sprout. A fourth element, Yevit, is a media art gallery on the bank rather than an island. Each shell is clad in a lighting system that turns the group into three illuminated forms after dark, which is when the complex actually reads as intended.

On screen. Avengers: Age of Ultron (2015) is the reason many visitors know the name. Marvel's second unit worked in Seoul over roughly two weeks in the spring of 2014, with support from the city and the national film council, and used Sebitseom as the exterior of the U-Gin Genetic Research Centre — the laboratory of Dr Helen Cho, where the regeneration cradle is kept and where Ultron begins constructing the synthetic body that becomes Vision. Two clarifications matter. First, only the exteriors and the surrounding river are Seoul: the laboratory interiors, like the great majority of the film, were built and shot on stages at Shepperton in England. Second, the film's Seoul is a composite. The sequence cuts Sebitseom together with Mapo Bridge, Gangnam-daero, the Cheongdam Bridge and the Sangam media district, so that the geography on screen is impossible to walk; vehicles cross the river in one direction and arrive somewhere that would require crossing it back. The city's own tourist authority has since mapped the locations, which is a fair indication of how much the shoot was worth to it.

What you actually see today. The islands are commercial venues rather than a park. Gavit holds a convention and banquet hall used heavily for weddings, along with restaurants; Chavit and Solvit hold restaurants, cafes, a rooftop terrace and event spaces, and the programme changes with tenancies. Walking on and around the decks is free, and many people come only for that — the footbridge, a circuit of the outer deck, and the view back across the water. The complex sits directly alongside the Banpo Bridge Moonlight Rainbow Fountain, a line of nozzles roughly 1.1 km long mounted on the bridge deck, which throws lit water in arcs into the river for around twenty minutes at a time, several times each evening from spring to autumn. The fountain is best seen from the Banpo park lawn just upstream of the islands rather than from the islands themselves.

The park it belongs to. Banpo Hangang Park is one of the more used stretches of the riverside system: a continuous cycle path, rental bicycles, convenience stores that function as improvised evening restaurants, a floating swimming pool in summer, and lawns that fill with delivery-food picnics on warm nights. This is ordinary Seoul at leisure, and it is a more interesting reason to come than the film credit.

Getting there and timing. Express Bus Terminal station on subway lines 3, 7 and 9 is the usual approach, about fifteen minutes on foot through the underpass to the river; Sinbanpo station on line 9 is marginally closer. The riverside paths and the footbridge are level and step-free. Go in the evening: the islands are unremarkable in daylight and become the thing they were designed to be once the cladding lights, ideally on a summer night with the bridge fountain running. Spring and autumn give the most comfortable riverside weather; winter wind off the water is severe, and July brings both heat and the monsoon.