The short answer
The Castlemap atlas maps 100 landmarks in Wales: 51 castles, 4 fortresses, 3 palaces & châteaux and 42 ruins — each with a photo, its story and a page of its own.
Figures published elsewhere often run higher still, because they count vanished sites and every surviving fragment of wall.
What a published source says
about 400 castles built at one time or another · over 100 still standing, as ruins or restored buildings — the Wikipedia article “Castles in Wales”.
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
88 of the 100 carry a sourced founding date. They run from c. 50 to 1850.
See them all on the map of castles in Wales →