What would be the optimal geography for a thriving capital, located in a caldera ?

I'm building a fantasy world with multiple intelligent species and civilisations. There is magic in this world, but also magical creatures that represent a serious threat to life in wild areas. Overall, the level of advancement I had in mind would be equivalent to the bronze era.

I though that a caldera would be an interesting geographic setting to place the city that would be the heartland of my Lizardmen empire. The geological formation could have indeed served as a natural fortification against magical monsters in ancient times. Over time, the city would have continued to grow thanks to its rich soils and the development of primitive geothermal technology. With a little lore building it would have finally developed into an economic, religious and political center (in a similar fashion to the sudden growth of some city during the bronze age)...

That's the main idea anyway. I am still unsure on many points and would appreciate to get external help/critics to improve my idea. Here are some open questions I have :

  • What would be the lowest possible elevation for a big caldera to form at ?

  • Is it possible to have caldera/volcanoes in an area without to much relief ? (in order to be accessible and part of major trade routes)...

  • What size should the caldera be (big enough for a bronze-era city) ?
  • Would the presence of a permanent lake inside the caldera help the growth of the city ? I wonder if a caldera-lake can even constitute a long term drinking water supply, because of pollution generated by the city itself... if it is indeed an issue, is there a way to create a setting with a another fresh water supply : a river, underground sources maybe ?
  • Could there be realistic speaking high-yield mining galleries in the area (there is no surface mining in bronze age...) ?
  • Would it be more realistic to place the crop farms inside or outside the caldera ?
  • $\begingroup$ Hi @Pierre, welcome! SE is based on the idea of asking a single well constrained question, for which there can be a single best answer. At present you are asking a series of related questions, which is not what we need here. It seems to me though, that your queries might be well suited to being asked as a series of interconnected questions perhaps? $\endgroup$ Oct 4, 2019 at 0:04
  • $\begingroup$ Furthermore, are you familiar with the Phlegraean Fields? $\endgroup$ Oct 4, 2019 at 0:04
  • $\begingroup$ Thank you for the welcome. I tried to be more specific by showing my own personal interrogations, but the only real question I need ansewered is the one from the title/first sentence. I overdid it a little, I'll try to keep it in mind in the future. $\endgroup$
    – Pierre
    Oct 4, 2019 at 0:41
  • $\begingroup$ The Yellowstone Caldera (in the Yellowstone National Park in the U.S.A.) is the caldera of the supervolcano. It has lakes, springs, geisers, hot pools, and so on; it has an elevation of 9000 feet (2800 meters) and its area is over a hundred square miles, enough for a bronze age country. At the other extreme, the Phelgaean Fields in Europe, also the caldera of a supervolcano, are partly under the sea and partly on the sea shore. $\endgroup$
    – AlexP
    Oct 4, 2019 at 5:31

1 Answer 1


IMHO you don't need too much technical expertise to write a realistic caldera city, since it's ancient and has expanded a lot. From ancient (human) cities we know that walls came and went on battles, but also city growth. It was usual for commoners to start building outside the walls, set up shops in the main routes, effectively expanding the city itself. Your Caldera can be like that. Old markings as where the walls once were, centered in the caldera and forever ever carving down to make more space for even more inhabitants, some with planning in mind, most without it, relying on hired excavators and architects to dig wherever they could. It would not be surprinsing to find surface level buildings too, either military of from the poorest classes.


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