While I am not excited by #ttrpg rules as such, I do love #worldbuiling , including detailing the region any campaign takes place in.
My current project is "rebooting" a setting I first started working on more than 20 years ago. I've started with a new, procedurally generated geography, and I am now placing the many locations I came up with back then into this new context - changing or removing those who seem too cringe-worthy to my now more experienced eye.
Once that is done, I can develop and place new locations.