Can be upgraded up to level 100.

The gold pit produces gold.

The higher the upgrade level of the gold pit and your character level, the more gold is produced.

As gold is only produced if there is capacity left in the gold pit, you need to claim your gold regularly.

Upgrade levels higher than 15 are only unlocked after upgrading all other buildings to their maximum. From level 25, gold is being produced while upgrading the gold pit.