The short answer
The Castlemap atlas maps 39 landmarks in Indonesia: 3 castles, 24 fortresses, 11 palaces & châteaux and 1 ruin — each with a photo, its story and a page of its own.
Wikidata, the open database this atlas is built from, holds 396 items in Indonesia that are a castle, fortress, fort, château, palace, citadel or fortification of any kind — from a royal residence to a single surviving tower.
Figures published elsewhere often run higher still, because they count vanished sites and every surviving fragment of wall.
Why the numbers differ
What counts as a castle. A hilltop ruin, a fortified manor, a Baroque palace and a 19th-century folly are all “castles” in ordinary speech, and every count draws that line somewhere different.
Standing or vanished. Most fortifications ever raised are gone. A count of sites is a multiple of a count of buildings you can walk into.
Who did the counting. A national heritage register, an enthusiast’s database and an open dataset each stop at a different threshold of evidence.
What this atlas counts
26 of the 39 carry a sourced founding date. They run from c. 650 to 1976.
See them all on the map of castles in Indonesia →