The Silo increases a player's maximum money capacity by $3000. It is typically advised not to use a silo. If a player has too much money, spending it is always better strategically. Silos are typically built by new players who are not aware of this. If a player is at maximum money capacity the game will send a warning by saying "silos needed".
When a silo is destroyed, the money it stores is lost.
The silo is not to be confused with the missile silo (atom bomb).