RESEARCH ARTICLE Geospatial Analysis of Historical Cartographic Data of Kollam Fort Ekta Gupta 1,2 • M. B. Rajani 1 Received: 13 April 2020 / Accepted: 14 September 2020 / Published online: 24 September 2020 Ó Indian Society of Remote Sensing 2020 Abstract The port of Kollam (Quilon) in Kerala had been an important trading centre for many centuries. Its significance as a landing point for traders is evident from its colonial history when there were repeated attempts to take over possession of this location. Being an important site, Kollam was frequently mapped by Europeans from the sixteenth to nineteenth centuries. The historical maps and views of Kollam contain vital information about the history, archaeology and geography of the area. Remote sensing and GIS can provide a real-world spatial context to these archived geographical documents of varied scales and types, drawn at different times spanning more than four centuries. The present study harnesses the potential of RS and GIS in integrating information present in the maps of such heterogeneous nature to advance the historical and archaeological knowledge of the Kollam fort. The integration of the maps of the different time, scale and style with the help of RS and GIS yielded information that was previously unknown. The present study has discovered the extant remains of the Portuguese and the Dutch fort that were not identified before and contributed to the scholarship on the construction, restoration, the extent and usage of the fort during its occupation by various European powers. Keywords Kollam Á Quilon Á Historical maps Á Colonial forts Á Remote sensing Introduction Kollam in Kerala, India, has historically been an important trading port. The port was confined to the promontory, now called Thangassery, which is 3 km west of Kollam Junc- tion railway station. This port was frequently visited by Chinese and Arabic as early as the seventh and eighth century (The Imperial Gazetteer of India 1908). It had also been of great interest to Portuguese, Dutch, British (each spelt the toponym differently; Covlao/Covlam, Coylan/ Coylang and Quilon, respectively) and local South Indian during the colonial period (Aiya 1906), which in India spanned from sixteenth to twentieth centuries. Portuguese established a factory 1 in Kollam in 1503 (Mathew 2017). Francisco de Almeida, the first Portuguese viceroy to India, had conquered this place in 1505 and a fortress called Fort St. Thomas was built in 1519 (Diffie 1977; Mathew 2017) which was later expanded to a larger fort (see ‘The For- taleza and the Portuguese Fort’ and ‘The Portuguese Fort (PF)’ sections). In December 1658, the fort was captured by Dutch United East India Company and then was re- occupied by the Portuguese in April 1659. In December 1661, Dutch finally took control of Kollam (Schilder et al. 2006), which they held for over a century. In 1795, Dutch factories and possessions were taken over by English East India Company (Aiya 1906). The port and the surrounding coastal stretch have been frequently map- ped by Portuguese (sixteenth and seventeenth century), Dutch (seventeenth and eighteenth century) and British (eighteenth and nineteenth century) at different scales and for various purposes. The maps have potential to enhance our understanding of the archaeology of the area. However, they sometimes may also have ‘inaccuracies’ due to primitive cartographic techniques, selective representation, agenda or purpose of making the map, the skill of car- tographer and scale or coverage (Gupta and Rajani 2020). Errors can also be caused during subsequent copying or reproduction (for instance, reverse printing or copying & Ekta Gupta ekta.geo@gmail.com 1 National Institute of Advanced Studies, IISc Campus, Bangalore, Karnataka 560012, India 2 Manipal Academy of Higher Education, Manipal, Karnataka 576104, India 1 Factory is a colonial term for entrepo ˆt. 123 Journal of the Indian Society of Remote Sensing (November 2020) 48(11):1567–1581 https://doi.org/10.1007/s12524-020-01181-w