The Marmaray Railway Infrastructure: The Challenges of the Heritage Protection before the Growth of Istanbul’s Urban Areas

The railway infrastructure has played a crucial role in urban development since its inception in the 19th century. This article aims to show how the transformations resulting from the implementa-tion of this transport system have had a particular impact on the city of Istanbul, considering a technical, an engineering and the heritage perspective. To achieve this, an exhaustive review of collected drawings, articles and reports has been carried out since 2012, while starting to work on the architectural coordination of the project. These documents reflect how the Marmaray project covers different aspects, such as materials, signage, civil protection and landscaping. The results obtained demonstrate how a railway infrastructure project not only improves the technical and operational efficiency of traffic in the city, but also protects the natural and historical heritage. As a main conclusion of this investigation, it highlights the necessity for proper coordination between technical interventions in the infrastructure and a comprehensive and integrated strategy that encompasses both the heritage and the urban landscape of Istanbul.