Green Ob has no dome?

[PlagueDoctor]

Hey all!

I have just begun this map and thus far enjoying it.  I recently tamed up a ptero and thought id give the map a little viewing.  So far it seems that there are only 2 domes? One for red ob (desert/fire place) and one for blue ob (snow biome). No dome for green ob though, or is there another dome somewhere?  
Any replies would be greatly appreciated! 

[DragonEnchantress]

idk but there is actually a 4th obelisk broken and under ground in the forest which kinda blew my mind lol

[RowletAlex]

Technically the city biome counts as a sanctuary (thanks to the obelisk) but it has no dome because it’s not a proto-ARK.

[Soursun]

there is a green obelisk, it is the city in the centre of the map. there is no orb there as its not got harsh conditions inside.

[DragonEnchantress]

I didn't think of the green ob protecting the city, that would make sense why the meteors dont hit in there then. I just thought they were being considerate that everyone is building in there xD;

[PlagueDoctor]

So if I understand this correctly, the blue and red ob are proto-arks (hence why they have a dome shield), whereas the green ob was the first full successful ark and thus no dome shield is needed.  Then I assume, the tech from the green ob was used in the rest of the arks in the sky that we all know and love.  Im also assuming that the blue ob in the sunken forest place was a possible failure of an ark/ob? 
Also thanks for all your replies guys!