Flatland is a personal domain, and website. The seeds of the idea go back over 30 years to the 1980s. A good friend of mine in high school gave me a book, "Flatland." I liked the name so much that a number of years later, in early 1992, I registered the domain.
I will leave a more fleshed-out version of events for another day. tl;dr: I let the domain lapse, I re-registered it in 1995 or so, and I've used it ever since for my personal email and various web-related servers, both stable and experimental.
Around the same time I registered the domain, I also started using it as a trade name. Originally unincorporated, then eventually as a proper LLC. The latter entity has its own website at flatland.tech.
Often paired with "flatland" was my handle "erewhon" which I have also used since the early 90s. Originally "erewhon" existed under "flatland", but I decided to registered Yet Another Domain purely dedicated to all things "erewhon".