Deca

They often have no bearing in logical architecture: some appear to be perfectly normal towers with shingles and doors and stairs, others are completely fantastical with winding impossible rooms and tiny porthole windows for doors.

Wizards -- powerful and terrifying, purposefully withdrawing from their morals and the society around them -- often move into these structures. Other creatures, like Spirits or Specters or wandering travelers and misfits, often find their homes here.

The Tower Maker never makes a tower which isn't needed, some of which go back thousands of years -- dead civilizations speak of the towers as old -- or appear in impossible locations. No one has been able to see it up close, instead, the only image had is a giant figure in the distance, slowly walking to the next tower to be built.