The palace is the most important building in every city.

It enables you to increase your total upkeep by 1000 per level and unlocks new buildings in the city. In order to upgrade your castle, in addition to the regular resources of gold, stone, and iron; you also need runes.

Dwarf palace
Dwarven Palace

Here we can see a perfect example of fine Dwarven craftsmanship. Not many are as skilled in the arts of masonry as the Dwarves. Beautifully detailed stone pillars and gold ornaments, the Dwarves take pride in their work. It is rumored that the greatest Dwarven masters can breathe life into stone, allowing them to shape it at their will. If a ruler (not of the Dwarven race) hired such hardworking artisans to build a non-Dwarven building, he would have to empty at least half or his treasury.

Elven Palace
Elven Palace

The Elven race lives in harmony with nature, their buildings are often constructed around trees and are masterfully crafted of raw materials held together by tree sap and resin. Many buildings seem to be alive as they shape and evolve simultaneously with the tree. Some generals tend to think that all it takes is one good storm and it's all reduced to a puddle. Subsequently they find themselves baffled by how much of a punch these walls can take! 

Orc palace
Orcish Palace

Orcish buildings are quite like a big slum. The main difference is that common slums are not full of sharp and pointy items and objects that 'magically' transform to a weapon in the hands of an Orc warrior. As tents and shacks get bigger, Orcs stabilize them with sharpened palisades which serve as a fine defense against cavalry. You can find all kinds of things inside, most of them dangerous, if not lethal.

Undead palace
Undead Palace

Once a place of peace and prayer, now a bastion of unholy magic and a sanctuary of the undead . Those who never visited such a place cannot even begin to imagine it's smell - not the smell of rot, but the paralyzing smell of sheer terror, as chills go down your spine. Built from moonrock and hardened obsidian, their austere buildings are made to devour life and corrupt their surroundings for centuries to come.