Wikidata

Readers ran the numbers on their own countries: Saxony alone has 700-plus historic fortifications against nine pins on the map; France counts roughly 180 listed castles against an estimated 45,000 nationwide.

One commenter guessed the map was only reading English-language Wikipedia before anyone confirmed it. Then the site's solo builder turned up in the replies, admitted the whole thing was built in a weekend, and promised to actually fix it.

The maker pitches AI agents plus community contributions and an 'agent ledger'. Commenters found stale figures, missing companies and badges that link to nothing.

The most useful fix offered: federate with Wikidata, which would pull in connections back to Crunchbase and other sources for free.

The data is Wikidata coordinates and opening dates; 96 stations were dropped for missing data. Between 1900 and 1930 'the map erupts'.

The submitter dropped a piece of trivia better than the viz: every Japanese station has its own stamp, and you can collect them in a notebook as a travel diary.