The Cloaking Lab allows you to increase the stealth rating on your ships by 5% per level. This is especially handy for transporting spies. All ships built at the shipyard on this planet will receive the increase. Existing ships are not retrofitted, they will need to be scuttled and rebuilt. All ships effected by this increase will have a slightly increased cost to build.
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.
The Embassy allows the formation of alliances. It is also a prerequisite to building the Space Station. Each level of the Alliance Leader's highest-level Embassy allows 2 more members to join the alliance. Alliance members need only have a level 1 embassy to participate.
The Espionage Ministry allows the construction of spy pods, or, at level 15, spy shuttles, at the shipyard. It also allows better offensive training of your spies. The higher the building level, the more effective your spies will be applying their trade.
Gas Giant Lab
The Gas Giant Lab does research on the gas giant settlement ship which deploys into a gas giant settlement platform. The gas giant settlement platform allows settlement of a gas giant. The higher the level of the gas giant lab the higher the level of the platform deployed from the gas giant settlement ship.
The Mining Ministry allows production of mining platform ships at the shipyard. The mining platform ship is deployed to asteroids where you can mine their ore. The ministry also allows management of deployed mining platforms and controls the flow of cargo ships to and from the platforms. You can control one platform per two levels of the mining ministry.
The Munitions Lab allows for the construction of robotic war ships. Warfare is hard to do in the vast reaches of space, so it's often simpler to install a spy on an enemy planet and have him run missions. Spies are relatively inexpensive, and you can use them over and over, whereas robotic war ships last for exactly one attack. However, war ships are pretty much guaranteed to be effective, whereas a spy can fail.
The Observatory allows the construction of probes and colony ships at the shipyard. It also provides a list of all your active probes and the stars they are observing. A higher building level allows more probes to be constructed. You may only have one Observatory on a planet.
Pilot Training Facility
The Pilot Training Facility increases the speed (3% per level), combat (3% per level) and stealth (3% per level) of the piloted ships you build at the shipyard. Existing ships are not retrofitted, they will need to be scuttled and rebuilt. Piloted ships affected by this increase will have a slightly increased cost to build. You may only have one Pilot Training Facility on a planet.
Propulsion System Factory
Work done in the Propulsion System Factory allows your ships to move faster through space by way of upgraded engines. Each level grants an additional 5% increase in speed. All ships built at the shipyard on this planet will receive the increase. Existing ships are not retrofitted, they will need to be scuttled and rebuilt. All ships affected by this increase will have a slightly increased cost to build. You may only have one Propulsion System Factory on a planet.
Shield Against Weapons
The Shield Against Weapons (SAW) is a railgun system that shoots down incoming enemy ships. It goes before other defensive measures such as drones and fighters, which can help save your drones and fighters for tougher battles. SAWs also help you defend your allies, as long as they are in the same star system as you. If an enemy ship is incoming to any world in a star system, then all allied planets will fire their saws at the incoming enemy ships.
The Shipyard is where the construction of your empire's ships takes place. The types of ships that can be built in the Shipyard are dependent on some of the other buildings on your planet. The higher the building level the faster ships are produced. In addition, you may have one ship in your build queue for each level of the shipyard.
The Space Port is the hangar and control tower for your ships. Here you can monitor your ships that are in transit, docked, or performing other tasks. The Space Port can hold double its level in ships in what are called docks. Multiple spaceports are shared and contribute to the total number of docks. The highest level spaceport on a colony counts as that colony's berth size when considering what ships can be launched. For example, a colony with it's highest spaceport at level 5 would be able to only launch ships with a berth size of 5 or less.
The Terraforming Lab is where research is done on the production of terraforming platform ships. Terraforming platform ships deploy into terraforming platforms which allows you to colonize planets your species wouldn't normally be capable of colonizing. The level of the building determines the level of the platform that is deployed from the ship.
The Trade Ministry allows access to the interstellar market. Through it you can set up trades for resources, glyphs, plans, ships, and prisoners with other empires. It also allows for pushing resources, glyphs, plans, ships, and prisoners between your own colonies. The newest features also allow for the automated pushing of resources to other bodies via the Supply Chain, and the removal of waste using the Waste Chain. The effectiveness of each of these chains is reduced if the efficiency of the Trade Ministry is reduced.