The Vermilion Royal Capital was the largest city in the Vermilion Kingdom and the entire human domain as a whole. There were about thirty districts and hidden underground tunnels and shelters that were unknown to the public.
It was rumored that these tunnels were built by the second king of the Vermilion Kingdom, Bloodbane Vermilion II, also known as the most ruthless king in the world.
The people of the human domain commonly referred to him as the Demon Lord of the Human Continent.
During his reign, the kingdom waged so many wars with the neighboring five kingdoms. Though millions didn't die in this war like the Great War of Rebirth, the deaths easily surpassed five hundred thousand.
The wars had become so intense that King Bloodbane had instructed the kingdom's [builders] and [architects] to build the tunnels and underground cities to safeguard the kingdom's valuable treasures and relics.