This post is in the spirit of "big-lists" on tex.se and other sites
Purpose of this post...
...is to collect (in separate answers, unless clearly related) open datasets containing detailed geospatial information.
The datasets should be worldwide or covering at least areas exceeding single counties or small (sub-)continents.
I believe the other restrictions already limit the sets substantially. In terms of content anything is fine, as long as it contains detailed geospatial information, be it raster-data, point data or.
To me, info that is built into standard packages (such as a worldwide city list) is boring. It's left to the community and the rating system to discourage those.
Post a link and a brief description of what the data contains.
If this resonates sufficiently (five or more answers which aren't mine) I'll place a bounty of 100-200 to reward the user with the most above average ranking answers (most likely just the highest ranking answer).