This wonder has no tech requirements; it can be built from the start of the game.
Great Tunnel
Each square around the city where this wonder is built that is already
generating some production produces one extra shield resource.
Requires
Burrowing technology.
Antigrav Control Center
All player's
antigravity
units will regenerate 50% of their hitpoints each turn.
Requires
Antigravity technology.
Oceanic Downtown
Each oceanic city center generates 3 points more trade and production.
Requires
Ocean Cities technology.
Can be built only in oceanic city.
Monument of Co-operation
All player's
native alien
units will regenerate 50% of their hitpoints each turn.
Requires
Alien Rights technology.
Protector
Provides additional protection against radiation making
max city size bigger by 2.
Requires City Defense technology.