International architecture practice Sasaki Associates have unveiled an ambitious masterplan for the largest mixed-use development in Southeast Asia: an island-based metropolis in Malaysia called Forest City.

The studio – whose previous work includes waterfront parks and river walkways in Chicago and Los Angeles – have envisioned “a compact and walkable metropolis with a variety of civic, cultural and recreational amenities set in a lush, tropical landscape with unparalleled ocean views.”

The SNG$58.3bn (US$40.7bn, €37.2bn, £28.1bn) project will cover an area of 3,954 acres across four man-made islands in Iskander Malaysia, one of the region’s most important trade and development corridors.

The city will combine residential, commercial and financial buildings with a variety of creative industries and leisure facilities. High rises and green parks will intermingle, looking out towards the ocean and the surrounding marine Seagrass Preserve.

“Forest City is a result of the region's remarkable growth," says Michael Grove, the principal in charge of the project at Sasaki. "Greater connectivity between Forest City and Singapore will further enhance the symbiotic relationship of cultures, economies, and the environment in this exceptionally diverse part of the world."

The project will feature extensive ground-level parks, a waterfront trail system and, according to local reports, a 50,000 capacity stadium for the Johor state football team.

“Linking the entire development is a pedestrian-centric rooftop network of interconnected parks and gardens located on the top level of an infrastructure podium,” said the architects in a statement. “This approach establishes a publicly accessible landscape as a continuous urban structure and is a defining element, creating the world's largest green roof system.”

Forest City will have a sophisticated multi-layered transportation network, integrating roadways, car parks, a light rail transit system and pedestrian paths. A ferry and high-speed rail line will connect the islands with Singapore and the Malaysian mainland.

The project is a joint venture between Chinese property developer Country Garden Holdings and state-owned company Esplanade Danga 88.

According to the developers, the project will be gradually implemented over the next 20 years.

Forest City joins a host of other tree-lined mixed-use schemes in development, including a Thomas Heatherwick-designed project in Shanghai and an eco-friendly project in Cairo visualised by Vincent Callebaut Architectures.

A separate long-term, mixed-use scheme in Iskandar – called Iskandar Waterfront City – is also in development. It will feature a theme park and an opera house among other leisure facilities.

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