Short answers, pulled from the story.
Idrakpur Fort was built in the year 1660 by Mir Jumla II, the governor of Bengal under the Mughal Empire. The structure rose from the muddy banks of the Meghna River as part of a triangular defense strategy to crush piracy.
Idrakpur Fort is located on the banks of the Meghna River and serves as the center of a three-point strategy that includes the Hajiganj Fort on the western bank of the Shitalakshya River and the Sonakanda Fort on the eastern bank. This triangular formation traps any pirate fleet attempting to navigate the junction of the Meghna, Shitalakshya, Ichhamati, and Dhaleshwari rivers.
Idrakpur Fort features a circular drum that stands 32.5 meters in diameter and 9.14 meters high, enclosed by a secondary fortification wall. The fort walls run 86.87 meters from north to south and 59.60 meters in width, featuring thick brickwork and machicolations from which enemies on the river could be targeted.
Idrakpur Fort was constructed to crush the very idea of piracy and protect the province of Bengal from Portuguese and Magh pirates who used the region's complex river network to loot wealthy cities. Mir Jumla II designed the fort as a kill zone where the water itself became the executioner for any aggressor.
A staircase leads from the main structure of Idrakpur Fort down to a secret underground chamber that functioned as a magazine or storehouse for arms and explosives. This hidden room was accessible only through a concealed passage and added a layer of mystery to the fort's history.