Stone Pile

Overview
The Stone Pile helps your Stone Quarries and/or Advanced Stone Quarries increase their output by +10%, at the cost of 20.

They cause any nearby Houses to experience a drop in tax rate of -5%.

Each Stone Quarry can handle two Stone Piles for a maximum of +20% production.

Early in the game, if the player can afford one of these, then the player should probably consider making use of it. Later in the game, with many more options open to you, these are attractive but not nearly as pressing.