The Castle Corpus

A gigantic elemental-cum-construct, the castle is a single building large enough to hold a city of 20,000, perhaps 30k for a limited time.

The city-castle is rooted in place over a ley line nexus, drinking pure mana from the earth below. This power is turned into life, sustaining the vast elemental.

Its purpose is to be a city, the best it can. Its mind is distributed, faint throughout such a large space. It operates on instinct, providing light, water, heat.

In perfect circumstances the city chooses willing wardens, about 20 (one per thousand occupants). These wardens form a deeper link with the city, allowing it to think more like a human, to better ‘hear’ the needs of its people. They also speak as its voice, coming together in a circle to communicate the city’s needs. In times of war wardens might be chosen against their will. (Think like the guardian kings from Atlantis: the Lost Empire.)

The city, if fully in possession of wardens, can make major changes over time. Farmland tills itself, walls grow for defense, rooms move from inside to outside of the city, inch by inch. And, of course, the building repairs itself.

The shape of the city, overall, is like that of a tree stump. It has a central tower, broad and ridged, that narrows as it climbs to a flat top. The ridges, below, turn to roots that push out from the city organically to meet the water and meander between fields.

The city’s favorite placement is atop a nexus where the elements meet: a shore, ideally with volcanic activity nearby. Somewhere like Reykjavik is ideal: mountains, volcanoes, sea, thin Northern air. While the city is stationary, it was once possible for a council of powerful mages to move it along leylines from nexus to nexus, at least in theory.