Population: 100,000-1m+.
The largest variety of settlement in Last Odyssey campaigns and also the least common by far is the metropolis. To give an idea of how rare these cities are, in the year 1100 CE on Earth there were no cities with a population of greater than 1 million, while the only two cities in the entirety of what we today would consider to be Europe that would count as metropoli under this definition were Constantinople and Cordoba. Of course, population alone does not make a metropolis, but rather the fact that it is large and storied enough to stand above the other cities in the overworld. The history of a metropolis will span several millennia, and GMs should represent its scale by including multiple nodes that represent different distinct parts of the city. It is not a trivial thing to traverse a metropolis, and the navigation difficulty and danger rating of moving between districts will be greater than zero, especially for foreigners. Not only is the dizzying array of goods and services present in a city present in metropoli, but also many unique ones, including both those tailored to life in the city and those tailored towards the elites that populate it, including everything from local guides to strange machinery to local forms of art.
Mapping the layout of a metropolis is by no means a trivial task. GMs should highlight major thoroughfares, important districts, and the places where different local elites live and work. Of course, much of the character of a metropolis depends on why, exactly, it exists in the first place. In a time when food still takes a great deal of labor to produce, one million people don’t just gather together for the fun of it. Many historical metropoli, such as Rome, Baghdad, or Kaifeng, were the political capitals of large empires, and contained numerous unique monuments, temples, and landmarks that made them distinct from other cities in the surrounding region. There will also often be services dedicated to helping people get around, such as the canalboats of Venice or the drawn carriages associated with Victorian London. Mechanized public transit is an invention of the industrial age, and its absence means that different districts will often have their own distinct culture and even sometimes their own accents.
Over the course of a campaign, players will most likely encounter one or two metropoli, and will spend a great deal of time there as well. Thus, GMs should take extra consideration to make them feel compelling and unique. Here are some things to consider: