I am working on a series of books set in the same world which I created. Most of my writing is medieval style. It has several countries and for each one I created an information page so I can keep track of what I have created there. I also have a rough map so I know where all my major cities and sites of significance are. On the lands pages I include things like building descriptions, terrain, what goods the area is known for, which characters originate from there, as well as what religion they use and what other races or creatures are native to the land. A lot of my stories take place in castles or the countryside and wilderness so I do not do much with cities but I am working in that direction.