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Death's Domain
From Discworld & Pratchett Wiki
Death's Domain is a realm outside of space and time. This is where Death lives together with his manservant Albert and his horse Binky. Almost everything in Death's Domain is in different shades of black where it isn't deep purple or shroud-white. Lilies grow in abundance and perfume the air. A later addition are the fields of billowing corn blowing in a non-existent wind, which remind the Reaper Man to take good care of the harvest.
Death's library
Death, like most passionate about their job, likes to keep a record. Death's library, which is peculiar in more than one aspect, serves as a kind of record of the Discs living (and non-living) population.
The library is unique in several respects;
Firstly, its collection consists entirely of biographies. As a record of all living (and dead) creatures, the library is huge and old, so huge that inside the library space and time are merely suggestions, not in any kind of way rules or laws... It's so old, that among the earliest works are stone tablets and wood carvings. Secondly, the books in the 'more recent' library are constantly writing themselves, describing the lives of their subjects. Some are short, sad little books, some are expanded into multi-volume grimoires (or, in the case of Albert, still expanding). Books in the older sections of the library are silent, their subjects long dead.
Before Mort came along, the only regular reader was Ysabell, who liked to read romantic stories about princes and princesses. Now once more, the books lay there, quietly scribbling among themselves, plotting out the lives of those that live on the Disc. The library will work as long as Death himself works, until great A'tuin reaches the end of his journey and the Disc comes to an end.

