Facebook has spent the best part of the past 22 months letting people populate their profile pages with location check-ins made via their mobile devices.
Going up against the likes of FourSquare and Gowalla, which it eventually bought and closed, Facebook wanted to capture content, location and interaction between users when on-the-go.
Whether Facebook Places has been a barn-storming success is open to debate, but what it has managed to achieve is the collection of millions of items of data about its users.
In a blog post released this week, Facebook has identified and published the most popular places in cities around the world where users have been checking in since the summer of 2010, either via the Facebook mobile service or on other third party apps with the relevant integration.
While on the one hand the results are interesting for what they say about Facebook users (lots of concert and sport venues, inevitably, and things like that), once again it is the data - and the Big Data - where this all gets very interesting.
The Four Seasons hotel in Tokyo will no doubt be delighted that it's the fifth most popular place in Japanese capital, according to the check-in data, but the most valuable part of such a revelation would be in the information contained in the profile of the user "checking in".
Likes, interests, age, relationship status, sex, groups, education, employment, etc - gold mine data, in other words.
Facebook doesn't pass on or sell this data (yet), but the smart organisations will be working out how to lure such users to their pages from the check-ins, urge them to become "fans" and capture their attention (and data) that way.
Anyway, for the curious, here are some of those cities and their most popular spots to check-in on Facebook.
Berlin and London:
New York City and Melbourne:
Paris and Sao Paulo:
Seoul and Tokyo: