From Civ World

The Palace is a special Building in the City. Every player starts with a Palace at the center of their city map. The Palace produces a small income of all five resources every five minutes (commonly called "trickle" by players), and the citizens will come here to deliver their resources unless there is another drop-off location closer to them.

The "trickle" rate for each resource = (2 + pop)*(1 + bonus/100), where "pop" is your current Population, and "bonus" is the percent bonus you have for that particular resource. Do note that while "trickle" occurs even when not playing the game, it will not build up while the player has too many unspent Harvests.

The Palace cannot be moved and it can only be upgraded by the following:

• By winning the Court of Camelot auction.
• By completing the Wonder Event of the Renaissance, you can increase your Palace from Small to Modest.
• By completing the Wonder Event of the Industrial Revolution, you can increase your Palace from Modest to Large.

An example of a Level 1 Palace with the Player rank of Duke or Duchess	A level 1 Palace as King or Queen of the Civilization
Eventually your Palace may reach as high (or higher) than this: A Level 3 Palace as a Prince or Princess