Billed as "the place where China meets the world," the China World Trade Center has, since opening in 1990, brought Beijing its first Starbucks, housed the capital's finest luxury stores and hosted business travelers, residents and office workers.

Now, a planned collaboration with Los Angeles-based 5 Plus Design is preparing to implement the WTC's next phase of expansion, by emulating the interconnected nature of Hong Kong multiplexes, the firm said.

"One of the things that sets this project apart from other multi-use developments in China is the opportunity and drive to create interconnection," said Michael Ellis, one of 5 Plus' two managing principals. "There is great potential here to create an unusually unified campus within the city of Beijing, with a truly integrated character.

"When we started working on the project, neither ourselves nor the World Trade Center really understood how great the potential was to knit all the different elements together. We've really opened each other's eyes, and I know we're all excited about the ultimate change it will bring to Beijing," he said.

Located on 17 hectares (42 acres) in the city's central business district, the WTC already has three hotels, two apartment towers, five office buildings, an exhibition center and a luxury mall. The expansion will provide additional midmarket retail and entertainment options, rooftop gardens, restaurants and bars.

The project is unusual in that most of the expansion will be built vertically within the existing space, Ellis said. The only demolition will involve the Traders Hotel, which is part of the current complex.

"What we hope to achieve is to strengthen [the WTC's] stature as a city icon by infusing the excitement of a vibrant retail expansion that focuses on making it the place for people to come to have quality leisure, entertainment and cultural experiences," said 5 Plus' China regional manager, Sern Hong Yu. "We already have the people, the crowds. However, the WTC lacks something which keeps them in to linger.

"Given the luxury of size and the large population it is serving, as well as the fame it has already with both locals and foreigners, we aim to have the WTC be the go-to place in Beijing."

The California firm has more than 20 other projects in China, including in Kunming, Chongqing and Nanjing. In recent years many Chinese developers have chosen to work with US designers and architects on multi-use projects, in collaboration with local firms that help foreigners navigate local codes. Ellis said 5 Plus is highly conscious of the importance of tailoring design to the local culture.

One factor in building in China is the focus on vertical expansion: A standard US retail multiplex is two to three stories; in China, shopping centers can reach seven levels. Offering entertainment or food options on upper floors helps drive traffic, Ellis said.

Catering to China's growing middle class is also a consideration.

"Although luxury stores already have a strong presence, we're hoping to integrate more mid-range tenants like Zara, H&M and various local brands to create a shopping center that doesn't feel too exclusive," the 5 Plus executive said. "There's a focus on integrating families, young office workers and different demographics. Larger retail projects with a wide range of offerings are still rare in China, but it's a global trend that's arriving there now."