Preserving historical mosques in their original designs enhances cultural heritage understanding and promotes the use of environmentally friendly local materials. This study investigates three historical mosques in the Gayo Highlands of Indonesia, each with similar designs but different maintenance approaches. One mosque retains its original design, while the other two have undergone renovations. The study evaluates the performance of these mosques in terms of thermal comfort and airflow. Field measurements of the indoor thermal environment were conducted over three days for each mosque. Simulations using ANSYS Fluent were also performed to predict airflow performance. Thermal comfort is assessed based on air temperature, relative humidity, air velocity, PMV (Predicted Mean Vote), PPD (Predicted Percentage of Dissatisfied), and SET (Standard Effective Temperature) values. The findings offer insights into how design and maintenance impact the environmental performance of historical mosques. This study indicates that the historical mosque maintained in its original design provides better thermal comfort than the renovated ones.