Large shield dome
The ultimate protective shield: ten times the shield of the small dome – also only once per planet.

The large shield dome brings a shield of 30,000 and a thick hull into battle. Like the small version it does not attack and can only be built once per planet. If it is destroyed, you can build it again.
To build it you need Energy technology level 8 and Shield technology level 4. Its shield grows with every level of shield technology. The Miner specialization and the Synth network boost it even further.
Background
The large shield dome defends against attacks up to a strength of 30,000 structure points. Like the small shield dome, only one can exist at any time. If it's destroyed, a new shield dome can be built.