Citadel of Knope
The Citadel of Knope protects your colony by redirecting damage of ships to itself whenever your defense force is unable to, meaning it is the last line of your defense. When it does this it loses a level. However, if it survives the impact it automatically creates a mirror replica of the ship that damaged it, thus giving the defender the ship that just attacked them.
Crashed Ship Site
The Crashed Ship Site allows you to add 5% to each of the stats / bonuses of each of your newly built ships per level of the Crashed Ship Site. And it does this without any additional cost to your ships, by allowing you to harvest alien technology from the crashed ship.