<p>The study area addressed in the present paper is the UNESCO World Heritage site, Ajanta caves of Maharashtra, India. The investigation aims to provide greater insights into the persistence of coolness and thermal comfort inside the caves. An in-situ assessment based on visual inspection is performed on the location, geography, and the internal and external design features of the caves, followed by measurement of thermal comfort parameters and microstructural assessment of stone samples collected from the site using Scanning Electron Microscopy (SEM). This study emphasizes various factors, including passive architectural and design features, environmental conditions, and inherent characteristics of basalt rock. The combination of the caves' geological location, the intrinsic behaviour of basalt rock, and design features of the structures collectively contributes to the persistence of coolness inside the Ajanta caves. In addition, the airflow patterns and temperature inside the caves are measured using anemometers. The airflow observations revealed the dominance of airflow near the entrance, and a diminishing airflow pattern towards the interior of the selected caves. The temperature within the caves also shows a similar pattern, with elevated levels near the main entrance that progressively diminish further into the depths of the caves. Overall, the SEM analysis disclosed the presence of water-retaining secondary minerals, which results in a cool and humid micro-climate inside the caves.</p>