MOBO Architects has won a design competition to refurbish vertical and horizontal access structures of a UNESCO-protected fortress in Cartagena, Colombia.

The London-based practice will revamp the 20,000sq m (215,000sq ft) area that surrounds the walled, colonial city with the aim of creating a pleasant walking tour through the city’s bastions and walls.

The winning proposal offers a series of urban interventions that will unify the existing disparate structures and create a continuous pathway for pedestrians and cyclists.

According to MOBO, the route will be customised “according to historical context, use of space and urban setting”. Corten steel will be in the main structural material used in elements such as walkways, stairs, ramps or handrails, while white concrete will be used in flooring surfaces and information points to act as a mimicry of the existing limestone. The walkways will be mainly made of wood to create a user-friendly environment.

As part of the landscape design, the footprint of the old destroyed part of the wall will be used as a water canal, guiding people along the historical edge of the city. The flow of water will go from the inside of the city, through the main wall-canal, towards the sea.

In 1984, Cartagena's colonial walled city and fortress was designated a UNESCO World Heritage Site, with the city boasting the most extensive fortifications in South America.