Sometimes the oldest solutions are the best. In China, where urban populations are rising rapidly, one design firm has turned to a model that is more than 900 years old as a basis for low-income community residences.

When developing the concept for its Tulou Collective Housing project – which is shortlisted for this year’s Aga Khan Award for Architecture – Urbanus, a Chinese firm, turned to the traditional tulou of China’s Fujian province. Built from the 12th century onwards, these circular, fortress-like structures of packed earth housed entire clans. The most famous of these, the Fujian Tulou, is a Unesco World Heritage Site.

Xiaodu Liu, a partner at Urbanus, believes the structure is well suited to low-income families, particularly migrant workers. First, the units that run around the perimeter can be designed to be extremely small and therefore rented at the lowest possible rates. This form of high-density housing can also be built on small plots of land.