W2/Main House
From Inselkampf
The main house is the heart of each and every island. Building orders are coordinated here. The more it is expanded, the more buildings can be built. Furthermore, the time required for building is thus reduced.
Upgrading this to level 5 allows the ability to build the Barracks.
Upgrading this to level 10 allows the ability to build the Laboratory and Harbor.
An island cannot be colonized unless the main house is reduced to level 0.