The “world-building” here is imaginative and grand in scale. The world of the “Books of Babel” are a little different from our own. The technological level is akin to the end of the 19th century; flint lock guns, canons and steam trains accompany Victorian era clothing and a similar level of social development. The “Hod” are slaves who do all the dirty and unwanted tasks within the tower. Anyone who commits a crime, becomes financially insolvent — or otherwise upsets someone important — becomes a “Hod” to work off the “debt” owed. The fantasy elements are for the most part underplayed, though there are “airships,” which are held aloft by balloons, and clockwork automata, along with, of course, the tower itself. The tower is huge, big enough to host entire kingdoms (known in the books as “ringdoms”) on a single level. No one knows how many levels there actually are; the upper reaches lost in clouds.
Source: latimes.com – Los Angeles Times