Can you read a city by its skyline? Seoul’s story would certainly be a page turner, an architectural rollercoaster ride from sleek commercial skyscrapers and blocky concept stores in Gangnam, to traditional hanoks in the north and a low-lying industrial factory district in the south, to soaring residential towers in the suburbs.

Fascinated by the diverse urban palette, architects come to Seoul to play – here, they can build their dreams, because anything fits. Audacious buildings conceived in moments of passion such as Rafael Viñoly Architects' Jongno Tower (1999), the Seoul City Hall by iArc Architects (2013) and Zaha Hadid’s Dongdaemun Park Spaceship (2014) were all born in Seoul.

Lotte World Tower, Kohn Pedersen Fox Associates, 2016. The design was inspired by traditional Korean material culture, such as the shapes of ceramics, porcelain and calligraphy. In an ode to Seoul’s urban evolution, a ‘seam’ runs from the top to the bottom of the tower, pointing towards the old city centre

Seoul is a truly modern city, a product of the late 20th century. It wasn’t until the late 1960s, a good decade after the end of the Korean war, that South Korea started to prosper economically. During the 1970s, key infrastructure was laid down; this included the Seoul Metro, now one of the largest and most advanced subways in the world, and bridges across the Han river linking the quiet Gangnam district to the rest of the city.

Twenty years of building ensued with enthusiasm, the population rising and density growing until a 21st century crack down. In 2008, the government hit pause and laid down strict planning regulations on floor-to-area ratios (FAR) in an attempt to control hyperdensity, restricting the reverie of architects and developers city-wide.

Shinsegae International, Olson Kundig, 2015. The 15-storey building is a flagship for the brand, containing offices, design studios, a ground floor retail space and restaurant, as well as a rooftop garden

Yet, what better than a challenge? Architects have become accustomed to pushing the limits of floor plans, materials and even gravity to meet the challenges of building in Seoul. At the 15th Venice Architecture Biennale in 2016, the South Korean pavilion, titled ‘The FAR Game: Constraints Sparking Creativity’, examined the phenomenon.

FAR limits in Seoul vary from 100 to 1,000 per cent, and in green belt areas drop to 50 per cent. Commercial buildings are allowed the highest FAR of 1,000 per cent maximum. It's worth noting that this drops to 800 per cent when building within the Four Gates, the central, historic area of the city (Article 55 of the Seoul Metropolitan Government Ordinance on Urban Planning 208).

Sinseol-dong Hanok, CoRe Architects, 2016. Using a cantilevered steel frame, the firm suspended a new build with living space above the original hanok, which they restored, bypassing all the traditional architecture and achieving a balance of new and old. Photography: Yong Kwan Kim, Moon Jung Sik, CoRe architects

In the past two years, as well as working within the FAR conditions, architects have become more conscious of their long-term contributions to the skyline. In recent years, closer attention has been paid to shape and materiality – as seen in Olson Kundig’s steel-grid-clad facade of the Shinsegae headquarters and the red brick exterior of the new Won & Won 63.5 by Doojin Hwang Architects providing respite from grey concrete monoliths.

FAR ratios for residential buildings vary in location across the city, from 100 to 250 per cent, in combination with other planning rules which accompany tricky inner city sites. The Darak Darak building by The_System Lab is an example of how architects are playing, and winning, at the game of FAR. A residential building for a family, with office and studio space below for the owners to rent out was built with a diagonal exterior wall skirting past restrictions of the densely surrounded site. Terrace balconies, not included in the FAR, were designed to extend living space and gabling the roof allowed for attic storage space, not included in the FAR. The list goes on.

KEB Hana Bank Landmark Tower, The_System Lab, 2017. The space looks to improve and enrich the customer experience though multi-purpose functions including cultural activity

Residential housing in Seoul was not always so space efficient. The traditional hanok, a single-storey house made of stone and timber with chunky gabled roofs and wide courtyards, can be found in certain areas of the city such as the Bukchon Hanok village and defies all the rules of space efficiency. In 2001, a hanok preservation plan was passed to protect the remaining hanoks across the city, yet, due to the cost of preservation – often more money than a plot is worth – developers either avoid them or find ways to demolish them.

Valiantly, CoRe architects found a way to preserve an old hanok and build a modern space-efficient house, designing a cantilevered steel frame to float a new structure above the old, bypassing the hanok, which they restored to glory. While the site, with 50 per cent FAR, was a limitation, the architects say that it was the only thing that saved the shabby hanok because ‘it was a complicated site that no one wanted to touch’.

Seoul Skygarden, MVRDV, 2017. Occupying a former overpass built in the 1970s,the regenerated space will also hold a Korean arboretum cataloguing local plants, as well as cafes and teahouses. Courtesy of MVRDV

A city like Seoul is always on the move. New projects opening this year include the KEB Hana Bank Landmark Tower by The_System Lab and the Seoul Skygarden by MVRDV (Seoul’s version of the Manhattan High Line). The inaugural edition of the Seoul Biennale of Architecture and Urbanism will launch in September 2017 with the theme of ‘Seoul as a city of humanity – Making a human-centered city’. There'll certainly be plenty to talk about.