GIS mapping of the historical Delhi–Lahore Badshahi Grand Trunk Road: Kos minars, Mughal–Sikh heritage and preservation imperatives in Tarn Taran, Punjab

This study documents eight extant Kos Minars within Tarn Taran District, Punjab, India, and employs GIS-based spatial analysis to reconstruct an approximately 42 km stretch of the historic Old Delhi–Lahore Royal (Badshahi) Road between Fatehabad Sarai and Sarai Amanat Khan, both ASI- and UNESCO-listed sites. Kos Minars served as route markers along historic highways that facilitated administrative, military and commercial movements. GPS-based field surveys were conducted at the sites. GIS analysis of the mapped sites, using QGIS, reveals that the inter-Kos Minar (IKM) distance along this section does not correspond to the commonly cited ∼3.2 km kos but instead aligns closely with the Akbari kos of approximately 4.19 km. GIS analysis depicts the alignment of the Kos Minars overlapping with a present-day driving road, demonstrating long-term infrastructural continuity. The study also highlights key Sikh-Mughal historical intersections along this imperial highway. The GIS-generated map revealed that Guru Arjan Dev’s large sacred pond (sarovar) megaproject aligns completely with the Kos Minars and hence the Badshahi Road. The Nurdi tomb along the royal road needs preservation, being a Mughal-era structure and of notable historical significance to Sikhs. Thus, by integrating field survey data with GIS-based analysis, the study generates updated evidence and quantitative metrics, emphasizes preservation necessities and highlights the utility of advanced geospatial technologies in enhancing heritage documentation and conservation frameworks. The study contributes to Sustainable Development Goal (SDG) 11 by supporting the documentation and safeguarding of historic cultural infrastructure through geospatial analysis.