Go 256:512
Think of it as a 10% silver tithe to the holder of the ES, from the Master of each Order in the kingdom.
It is not optional. Masters often regularly (nightly) purge their silver to their Citadels, Order Banks, alts, best friends, and so on. Especially after an OvO win.
Once at 256:512, click on the building entrance to open it. (Watch for the larger than usual gold square glowing for a moment. It can be problematic clicking the right spot - it merely growls at you when you get it wrong. Same as it does when you click on a lake or otherwise bare but uninhabitable tile.)
Once open, click the ? at the top left, and some explanatory text will come up.
Also, click the green enter button for more helpful text. Again, the ? at the top left has more info.
With reputations now being assignable every 3 hours ... I don't envy a kingdom's king ... catching requests for 13 different reputations every 3 hours from up to 40,000 players, would be extremely onerous and time consuming.