Jaffna Fort VOC siege defense: coral stone ramparts and subterranean powder magazines?

Jaffna Fort, established by the Portuguese in 1619 and expanded into a massive pentagonal star fort by the Dutch VOC in 1680, represents colonial military engineering. The ramparts are faced with fossilized coral limestone blocks quarried from regional coastal reefs. Deep inside the fortress bastions, Dutch engineers built subterranean powder magazines (Kruitmagazijn). To prevent fatal gunpowder explosions caused by dampness or lightning, these magazines featured thick double-vaulted barrel ceilings constructed from imported yellow Dutch clinker bricks (IJsselstenen) bonded with shell-lime mortar, surrounded by air ventilation shafts.