Is this your experiment? https://github.com/jkakavas/creepy https://www.geocreepy.com/
This one used data shared by the user (opt-in on sharing geolocation in the app or browser), which then is publically exposed through the API (like this feature says it would).
Mine doesn't give a shit, geolocation was shared even when turned off by the user in Twitter.
What it does is download all photos that the user shared on Twitter, extract GPS tags from EXIF, and put markers on Google maps, annotated with these photos.