Greyhawk was forever changed over a millennium ago when the Suloise and Baklunish empires blew each other up. The two empires had been at war for dominance of the continent of Oerik (where nearly all published adventures in the world are set) and their struggles had sent refugees North into the center of the continent where they came into conflict with the native populations. These refugees would form the bulk of the history of the land as we understand it, but it was the Baklunish-Suloise wars that would define the world.
The two empires were in a bitter struggle that saw them becoming increasingly hostile until the Suloise Empire acted in desperation and used a super weapon: The Invoked Devastation. This weapon would utterly cripple and destroy the Baklunish Empire, but not before their own super weapon would be unleashed on the Suloise in the form of the Rain of Colorless Fire. These weapons were more than just a magical spell; they would fundamentally reshape the land they were used on turning one area into the Dry Steppes (caused by the Invoked Devastation) and the other into the Sea of Dust (caused by the Rain of Colorless Fire).
Greyhawk, then, is a post-apocalyptic setting shaped by the world-altering repercussions of Baklunish and Suloise wars. The great ruins of the world are often old temples, cities, and fortresses leftover from those vast empires. As a result, it becomes incumbent upon us, as Dungeon Masters (DMs) running in the world of Greyhawk, to answer the fundamental questions of that time period: what sort of technological level did the two empires possess and what sort of architectural standards dominated their structures?
For my games I have decided that the Suloise and Baklunish empires were advanced technologically. How advanced? Sufficiently enough that they could create fissionable bombs, chemical warfare, traverse the stars, and create weapons of such devastation that to lesser advanced peoples they might appear as magical spells and artifacts.
There is some evidence for this line of thought in certain artifacts that could easily be advanced forms of technological machinery like: the Mighty Servant of Luek-O, the Machine of Lum the Mad, Queen Ehlissa’s Marvelous Nightingale, Heward’s Mystical Organ, the Ring of Gax, the Codex of the Infinite Planes, among others. Without question these artifacts could be magical in their origin as we have often treated them in our games, but if they are significantly advanced machinery then to less advanced eyes there would be no difference between them and actual magic. Indeed, if these artifacts were to be actual machinery instead of magical spells then it might better explain their odd workings and failings as no individual would willingly make a ring that randomly cause odd effects to occur or write a book that could kill the reader just by daring to open it.
This change makes the world of Greyhawk similar to the Old World of Warhammer Fantasy Role-Play (WFRP) as both are now viewed as post-apocalyptic worlds devastated by advanced technologies that have changed their worlds irrevocably. It also brings the world of Greyhawk closer to the pulp novels and stories that helped inspire the game (in particular books like Jack Vance’s Planet of Adventure and Edgar Rice Burroughs Mars and Venus Series).
When it comes to architectural standards for each empire, I think that Brutalism nicely fits with the often maligned Suloise Empire which is written of as though it were a brutal, authoritarian society where people betrayed, stole from, and murdered each other to advance in social rank. Brutalism echoes the authoritarian hallmarks and with these monolithic structures that dominate the viewer and oppress their sense of happiness and freedom.
For the Baklunish I’ve decided to use Art Deco as my architectural standard. By contrast to the Brutalism of the Suloise the Art Deco movement is open, beautiful and welcoming – yet it remains highly functional and resilient. It’s artistic, and has a distinct color palette that will help differentiate it from the Suloise.
By providing ourselves with an architectural standard for each of these two empires we have now given ourselves a quick-reference point to research when attempting to “build” a new tomb or ancient structure our players will be exploring within our world. We can research the actual floor plans for these buildings and repurpose them to our own needs. There are, of course, other architectural standards that you can use for each civilization but I encourage you to use distinct ones for each so that you can immediately provide your players with a reference point for who made them and what they wanted those who came there to experience.